Add a "how to contribute to docs section" to the docs

[asaikali]

A person wishing to contribute to the documentation for example adding a small section, clarifying some content has to figure out how to contribute to the docs. an occasional contributor might have 1 hour to improve the docs, but it is not obvious how long it will take to configure a tool chain to effectively contribute docs. I suggest adding a section on how contribute to the docs into the docs so that more folks can get going making contributions. The section should cover the following topics.

• How much time it will take to configure any environment to contribute to the docs. Ideally this can be 10 min or less to setup the env.
• what technology is used to write the docs
• steps for write, edit, view cycle on developer machine
• Links to a tutorial on the tech used to write docs for example asciidoctor cheat sheet
• recommendation for good editor plugins to make contributing to the docs easy

[rwinch]

I think this might be best kept in the CONTRIBUTING.md file