gplugin/gplugin

Remove some documentation about hgflow from HACKING.md as we don't use hgflow anymore

2021-03-22, Gary Kramlich
11c702036a0a
Remove some documentation about hgflow from HACKING.md as we don't use hgflow anymore

Testing Done:
Eye testing only.

Reviewed at https://reviews.imfreedom.org/r/579/
[branchname]
master = default
develop = develop
feature = feature/
release = release/
hotfix = hotfix/
support = support/