Create a meta list of documentation

[benlk]

This should cover:

• a list of documentation outside of INN/docs
• a list of things that aren't documentation, but are valued lists — private stuff shouldn't be linked, but maybe it should be described how to find it
• The slack :evergreen_tree: emoji and how it ties into friday meetings https://18f.gsa.gov/2015/12/08/using-emoji-for-knowledge-sharing/ which we've been doing since 2015 https://innorg.slack.com/archives/G0DSN1109/p1449769079001756
• A list of services that we no longer use, but that might be linked to in places
• WordPress/PHP @link and @see docblock comment standards
• what else?