Updates instructions on how to contribute to the documentation. (#291)

* Updates instructions on how to contribute to the documentation.
* Fixes typos in update to contribution documentation
* Eliminates whitespace

---------

Co-authored-by: Brandon Hill <[email protected]>

Author: bghill

docs/_docs/contributing/docs.md

@@ -41,14 +41,22 @@ cd {{ site.reponame }}/
 ### Install a local Jekyll server
 This step is required if you want to render your work locally before committing the changes. This is highly recommended to ensure that your changes will render properly and will be accepted.
 
+Jekyll requires Ruby. This project uses an older version of Jekyll, and thus requires an older version of Ruby (v2.7.8 seems to work). <a href="https://github.com/rbenv/rbenv">rbenv</a> is suggested to manage Ruby versions. On OS X, this looks like:
+
+```bash
+brew install rbenv
+rbenv init
+rbenv install 2.7.8
+cd docs
+rbenv local 2.7.8
+```
+This requires a new shell after installing rbenv (it modifies your shell profile). The last line sets Ruby 2.7.8 to be the Ruby version used within the docs directory. A second shell restart may be needed again, after that line. Test your active Ruby version with `ruby -v`. Once working, you install the needed plugins with (from the deid/docs directory):
+
 ```bash
-brew install ruby
-gem install jekyll
-gem install bundler
 bundle install
 ```
 
-Now you can see the site locally by running the server with jekyll:
+Now you can see the site locally by running the server with Jekyll:
 
 ```bash
 bundle exec jekyll serve