Apply suggestion from @negin513

Co-authored-by: Negin Sobhani <negins@ucar.edu>

Author: weiji14

docs/source/contributing.rst

@@ -142,7 +142,7 @@ Contributing documentation
 We greatly appreciate documentation improvements. The docs are built from the docstrings
 in the code and the docs in the ``docs`` directory.
 
-To build the documentation, you will need to requirements listed in ``ci/doc.yml``.
+To build the docs, you will need to install the requirements listed in ``ci/doc.yml``.
 You can create an environment for building the documentation using::
 
     conda env create --file ci/doc.yml