Inject extra help for the temporal flame graphs

Temporal flame graphs have just been inheriting the help text of normal
flame graphs. Update this to add a small section explaining how to use
the sliders to investigate a different time range.

Signed-off-by: Matt Wozniski <[email protected]>

src/memray/reporters/templates/flamegraph.html

@@ -44,6 +44,8 @@
   The flame graph displays a snapshot of memory used across stack frames at the time <b>when the memory usage was at its peak</b>.
 </p>
 {% endif %}
+{% block slider_help %}
+{% endblock %}
 <p>
   The vertical ordering of the stack frames corresponds to the order of function calls, from parent to children.
   The horizontal ordering does not represent the passage of time in the application: they simply represent child frames in arbitrary order.

src/memray/reporters/templates/temporal_flamegraph.html

@@ -26,6 +26,16 @@
 </div>
 {% endblock %}
 
+{% block slider_help %}
+<p>
+  Initially the report shows allocations made at any time and not freed before
+  tracking was deactivated. By using the two sliders on the bottom line chart,
+  you can select a different time range for analysis instead. The flame graph
+  will be updated to reflect allocations made within your chosen time window
+  and not freed within it.
+</p>
+{% endblock %}
+
 {% block flamegraph_script %}
 <script type="text/javascript">
   {%- include "assets/temporal_flamegraph.js" -%}