Update iotools description in api.rst (#1244)

* Update iotools description in api.rst

As far as I know there are no capabilities for writing to a variety of file types.

* Added "writing" capabilities to iotools description

Author: AdamRJensen

docs/sphinx/source/api.rst

@@ -463,8 +463,8 @@ Functions
 IO Tools
 ========
 
-Functions for reading and writing data from a variety of file formats
-relevant to solar energy modeling.
+Functions for retrieving, reading, and writing data from a variety
+of sources and file formats relevant to solar energy modeling.
 
 .. autosummary::
    :toctree: generated/