Update index.rst spell errors

Merge pull request #43 from bw4sz/patch-1

docs/python_api/index.rst

@@ -4,8 +4,8 @@ API Summary
 
 The EasyIDP package have the following modules:
 
-- :doc:`Point cloud Module <./pointcloud>` : read, write, check and crop opertation.
-- :doc:`GeoTiff Module <./geotiff>` : read, write, crop, and statistics opertation.
+- :doc:`Point cloud Module <./pointcloud>` : read, write, check and crop operation.
+- :doc:`GeoTiff Module <./geotiff>` : read, write, crop, and statistics operation.
 
   - :doc:`cvtools Submodule <./cvtools>` : processing ndarray images without install scikit-image.
 
@@ -39,4 +39,4 @@ Although it may seem like more code, advanced wrappers have more convenient func
 
     The :class:`easyidp.Container` object, its child objects, and objects contains this object, like :class:`easyidp.roi.ROI` , ``ProjectPool`` , ``Recons`` , ``Pix4D`` , ``Metashape``, can not be saved by pickle. 
 
-    Please check this link for more details `What can be pickled and unpickled <https://docs.python.org/3/library/pickle.html#what-can-be-pickled-and-unpickled>`_ .
+    Please check this link for more details `What can be pickled and unpickled <https://docs.python.org/3/library/pickle.html#what-can-be-pickled-and-unpickled>`_ .