Remove subsections from Vector Rendering properties section

Given that not all the options are in groups and only groups are put as subsection
the section structure can be misleading
(e.g. is "force layer to render" an option of "simplify geometry"?)
Also reorder options to match the GUI

# Conflicts:
#	docs/user_manual/working_with_vector/vector_properties.rst

docs/user_manual/working_with_vector/vector_properties.rst

@@ -3201,42 +3201,41 @@ Rendering Properties
 
    Layer Rendering Properties dialog
 
-Scale dependent visibility
---------------------------
+The |rendering| :guilabel:`Rendering` tab offers following properties:
 
-You can set the :guilabel:`Maximum (inclusive)` and :guilabel:`Minimum
-(exclusive)` scale, defining a range of scale in which features will be
-visible. Out of this range, they are hidden. The |mapIdentification|
-:sup:`Set to current canvas scale` button helps you use the current map
-canvas scale as boundary of the range visibility.
-See :ref:`label_scaledepend` for more information.
+* Under |unchecked| :guilabel:`Scale dependent visibility`,
+  you can set the :guilabel:`Maximum (inclusive)`
+  and :guilabel:`Minimum (exclusive)` scales,
+  defining a range of scales in which features will be visible.
+  Out of this range, they are hidden.
+  The |mapIdentification| :sup:`Set to current canvas scale` button helps you
+  use the current map canvas scale as boundary of the range visibility.
+  See :ref:`label_scaledepend` for more information.
 
-.. note::
+  .. note::
 
    You can also activate scale dependent visibility on a layer from within
    the :guilabel:`Layers` panel: right-click on the layer and in the contextual menu,
    select :guilabel:`Set Layer Scale Visibility`.
 
+* QGIS offers support for on-the-fly feature generalisation.
+  This can improve rendering times when drawing many complex features at small scales.
+  This feature can be enabled or disabled in the layer settings
+  using the |checkbox| :guilabel:`Simplify geometry` option.
+  There is also a global setting that enables generalisation by default for newly added layers
+  (see :ref:`global simplification <global_simplification>` for more information).
 
-Simplify geometry
------------------
+  .. note::
+   Feature generalisation may introduce artefacts into your rendered output in some cases.
+   These may include slivers between polygons
+   and inaccurate rendering when using offset-based symbol layers.
 
-QGIS offers support for on-the-fly feature generalisation. This can
-improve rendering times when drawing many complex features at small scales.
-This feature can be enabled or disabled in the layer settings using the
-|checkbox| :guilabel:`Simplify geometry` option. There is also a global
-setting that enables generalisation by default for newly added layers (see
-:ref:`global simplification <global_simplification>` for more information).
-
-.. note::
-  Feature generalisation may introduce artefacts into your rendered
-  output in some cases. These may include slivers between polygons and
-  inaccurate rendering when using offset-based symbol layers.
+* The |unchecked| :guilabel:`Fixed reference scale` indicates the map scale
+  at which symbology and labeling sizes which uses paper-based units (such as millimeters or points) relate to.
+  The sizes will be scaled accordingly whenever the map is viewed at a different scale.
 
-While rendering extremely detailed layers (e.g. polygon layers with a huge number
-of nodes), this can cause layout exports in PDF/SVG format to be huge as all
-nodes are included in the exported file. This can also make the resultant file
-very slow to work with/open in other programs.
+  For instance, a line layer using a 2mm wide line with a 1:2000 :guilabel:`Reference scale` set
+  will be rendered using 4mm wide lines when the map is viewed at 1:1000.
 
 * The :guilabel:`Selections` group allows you to control whether a specific color or symbol should be used
   in place of the defaults (:menuselection:`Project properties --> General --> Selection color`)
@@ -3252,13 +3251,17 @@ very slow to work with/open in other programs.
     then the default selection color is not applied at all;
     being able to set a specific simpler symbol to use for selected features in the layer can help.
 
-Checking |checkbox| :guilabel:`Force layer to render as raster` forces these
-layers to be rasterised so that the exported files won't have to include all
-the nodes contained in these layers and the rendering is therefore sped up.
+* Rendering extremely detailed layers (e.g. polygon layers with a huge number of nodes),
+  can cause layout exports in PDF/SVG format to be huge as all nodes are included in the exported file.
+  This can also make the resultant file very slow to work with/open in other programs.
 
-You can also do this by forcing the layout to export as a raster,
-but that is an all-or-nothing solution, given that the rasterisation
-is applied to all layers.
+  Checking |checkbox| :guilabel:`Force layer to render as raster` forces these layers
+  to be rasterised so that the exported files won't have to include all the nodes
+  contained in these layers and the rendering is therefore sped up.
+
+  You can also do this by forcing the layout to export as a raster,
+  but that is an all-or-nothing solution, given that the rasterisation is applied to all layers.
+  Alternatively, you can rely on geometry simplification in :ref:`layout export settings <create-output>`.
 
 * |unchecked| :guilabel:`Refresh layer at interval`: controls whether and how regular a layer can be refreshed.
   Available :guilabel:`Configuration` options are:
@@ -3275,22 +3278,12 @@ is applied to all layers.
 
   It is also possible to set the :guilabel:`Interval (seconds)` between consecutive refreshments.
 
-Depending on the data provider (e.g. PostgreSQL), notifications can be sent to
-QGIS when changes are applied to the data source, out of QGIS. Use the |checkbox|
-:guilabel:`Refresh layer on notification` option to trigger an update.
-You can also limit the layer refresh to a specific message set in the |checkbox|
-:guilabel:`Only if message is` text box.
-
-Use Scale Reference
--------------------
-
-If set, the reference scale indicates the map scale at which symbology and
-labeling sizes which uses paper-based units (such as millimeters or points)
-relate to. The sizes will be scaled accordingly whenever the map is viewed at
-a different scale.
+* Depending on the data provider (e.g. PostgreSQL), notifications can be sent to
+  QGIS when changes are applied to the data source, out of QGIS. Use the |checkbox|
+  :guilabel:`Refresh layer on notification` option to trigger an update.
+  You can also limit the layer refresh to a specific message set in the |checkbox|
+  :guilabel:`Only if message is` text box.
 
-For instance, a line layer using a 2mm wide line with a 1:2000 reference scale
-set will be rendered using 4mm wide lines when the map is viewed at 1:1000.
 
 .. index:: Temporal
 .. _vectortemporalmenu: