Update custom repo roles URL

[exageraldo]

Update the API routes, from /orgs/{org}/custom_roles to /orgs/{org}/custom-repository-roles, and some documentation references.

Fixes: #2700

[codecov]

Codecov Report

Merging #2702 (91d111e) into master (099fae4) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2702   +/-   ##
=======================================
  Coverage   98.05%   98.05%           
=======================================
  Files         131      131           
  Lines       11442    11457   +15     
=======================================
+ Hits        11219    11234   +15     
  Misses        152      152           
  Partials       71       71           

Impacted Files	Coverage Δ
github/orgs_custom_roles.go	94.23% <100.00%> (ø)
github/event.go	100.00% <0.00%> (ø)
github/messages.go	100.00% <0.00%> (ø)
github/event_types.go	100.00% <0.00%> (ø)
github/teams.go	98.18% <0.00%> (+0.04%)	⬆️

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[gmlewis]

I'm surprised that GitHub did not make a version update for a breaking change like this. I will review this later tonight.

[gmlewis]

Thank you, @exageraldo !
LGTM.

Awaiting second LGTM+Approval from any other contributor to this repo before merging.

[valbeat]

LGTM!

[gmlewis]

LGTM!

Thank you, @valbeat !
Merging.