Doc edits for the contributors guide

[artberger]

Part of a general doc sweep of existing content.

• Revised contributor guide for grammar, IBM Style
• Updated TOC
• Added documentation contribution guides

Signed-off-by: Art Berger [email protected]

[codecov]

Codecov Report

Merging #193 into master will decrease coverage by 0.66%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #193      +/-   ##
==========================================
- Coverage   75.79%   75.13%   -0.67%     
==========================================
  Files           5        5              
  Lines         756      756              
==========================================
- Hits          573      568       -5     
- Misses        135      139       +4     
- Partials       48       49       +1     

Impacted Files	Coverage Δ
controllers/service_controller.go	55.13% <0.00%> (-1.72%)	⬇️

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[JohnStarich]

Looks great, thanks!

I think some of the existing guidelines are out of date, but we can update those later 👍