add contributing doc pages

doc/source/contributing.md

+# Contributing Workflow
+
+abc
+
+

doc/source/contributing_docs.md

+# Contributing Documentation
+
+This guide assumes the reader has read the [Contribution workflow](contributing.md) for details about making changes to
+code within gstlal repo, since the documentation files are updated by a similar workflow.
+
+## Writing Documentation
+
+In general, the gstlal documentation uses [RestructuredText (rst)](https://docutils.sourceforge.io/rst.html) files
+ending in `.rst` or [Markdown](https://www.markdownguide.org/basic-syntax/) files ending in `.md`.
+
+Useful Links:
+
+- [MyST Directive Syntax](https://myst-parser.readthedocs.io/en/latest/syntax/syntax.html#syntax-directives)
+

doc/source/index.rst

@@ -45,6 +45,7 @@ The GstLAL software package is used for the following activities:
 
     local_environment
     contributing
+    contributing_docs
 
 .. toctree::
     :caption: API Reference