chore(conf): switch to new source_suffix syntax

Switch to the new source_suffix definition. Silences the following
warning:

Converting `source_suffix = '.rst'` to `source_suffix = {'.rst':
'restructuredtext'}`.

Signed-off-by: Randolph Sapp <[email protected]>

Author: StaticRocket

conf.py

@@ -48,10 +48,11 @@
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
 
-# The suffix(es) of source filenames.
-# You can specify multiple suffix as a list of string:
-# source_suffix = ['.rst', '.md']
-source_suffix = '.rst'
+# A dictionary mapping the file extensions (suffixes) of source files to their file types. Sphinx
+# considers all files files with suffixes in source_suffix to be source files.
+source_suffix = {
+    '.rst': 'restructuredtext'
+}
 
 # The encoding of source files.
 #source_encoding = 'utf-8-sig'