DannyCooper

Enables a knowledge base post type and section taxonomy.
The plugin adds a Knowledge Base tab to your admin menu, which allows you to add articles just as you would regular posts. This allows you to keep your articles even if you change theme.
The Apollo Theme was built purposely to work with this plugin – <a href="http://crtv.mk/ez5P" title="Apollo WordPress Theme" rel="nofollow ugc">Apollo Theme</a>
<h4>Bugs</h4>
If you find an issue, let us know <a href="https://github.com/DannyCooper/knowledge-base-cpt/issues" rel="nofollow ugc">here</a>!
<h4>Contributions</h4>
Anyone is welcome to contribute to the Knowledge Base CPT plugin.
There are various ways you can contribute:
<ol>
<li>Raise an <a href="https://github.com/DannyCooper/knowledge-base-cpt/issues" rel="nofollow ugc">Issue</a> on GitHub</li>
<li>Send us a Pull Request with your bug fixes and/or new features</li>
<li>Translate the Knowledge Base CPT plugin into <a href="https://www.transifex.com/projects/p/knowledge-base-cpt/" rel="nofollow ugc">different languages</a></li>
<li>Provide feedback and suggestions on <a href="https://github.com/DannyCooper/knowledge-base-cpt/issues?direction=desc&labels=Enhancement&page=1&sort=created&state=open" rel="nofollow ugc">enhancements</a></li>
</ol>

Knowledge Base CPT

Enables a 'knowledge base post' type and 'section' taxonomy.

Boone Gorges

CUNY Academic Commons

David Cavins

BuddyPress Docs adds collaborative work spaces to your BuddyPress community. Part wiki, part document editing, part shared dropbox, think of these Docs as a BuddyPress version of the Docs service offered by the Big G ifyouknowwhatimean
Features include:
<ul>
<li>Docs that can be linked to groups or users, with a variety of privacy levels</li>
<li>Support for fully-private document uploads</li>
<li>Doc taxonomy, using tags</li>
<li>Fully sortable and filterable doc lists</li>
<li>TinyMCE front-end doc editing</li>
<li>One-editor-at-a-time prevention against overwrites, plus idle detection/autosave</li>
<li>Full access to revision history</li>
<li>Dashboard access and management of Docs for the site admin</li>
</ul>
This plugin is in active development. For feature requests and bug reports, visit http://github.com/boonebgorges/buddypress-docs. If you have translated the plugin and would like to provide your translation for distribution with BuddyPress Docs, please contact the plugin author.

BuddyPress Docs

I used it on a project for a client several years ago and it worked like a charm. Also, it was well-maintained.

Knowledge Base CPT vs BuddyPress Docs