Update CONTRIBUTING.md in line with https://about.gitlab.com/handbook/engineering/#gitlab-repositories

Add CHANGELOG for 6.0.2

See merge request gitlab-org/gitlab-shell!187

Update gitaly-proto and gitaly libs

See merge request gitlab-org/gitlab-shell!185

Use grpc-go 1.9.1

See merge request gitlab-org/gitlab-shell!184

Fix git push by removing a bad require in the pre-receive hook

Closes gitlab-qa#158

See merge request gitlab-org/gitlab-shell!183

Remove special case treatment of Geo nodes for SSH

Closes #115

See merge request gitlab-org/gitlab-shell!179

We removed SSH support in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3553,
so we no longer need the ability to show all refs for Geo nodes.

Closes #115

Remove direct redis integration

Closes #119

See merge request gitlab-org/gitlab-shell!181

Resolve "Remove bin/gitlab_projects and lib/gitlab_projects.rb"

Closes #113

See merge request gitlab-org/gitlab-shell!180

Introduce a more-complete implementation of bin/authorized_keys

Closes #118

See merge request gitlab-org/gitlab-shell!178

bin/authorized_keys doesn't check that the requesting user matches the expected
user, so to enable database authorized keys lookups, we currently ask the admin
to create a custom script for that purpose.

Better is to have a complete script that can perform the whole task. This commit
introduces bin/gitlab-shell-authorized-keys-check which does so.

Remove unused redis bin configuration.

Closes #114

See merge request gitlab-org/gitlab-shell!177

Prints a message if project was renamed

See merge request gitlab-org/gitlab-shell!175

Use 'git clone --no-local' when creating a fork

See merge request gitlab-org/gitlab-shell!176

Add a 'fork-repository' command that works with hashed storage

Closes #116

See merge request gitlab-org/gitlab-shell!174

The existing 'fork-project' command cannot work with hashed storage as
the source project basename differs from the destination repository
basename. It is deprecated by the addition of 'fork-repository' and should
be removed in the next major version.

Add relative git object dir envvars to check access request

See merge request gitlab-org/gitlab-shell!171

translate gl_username -> REMOTE_USER

See merge request gitlab-org/gitlab-shell!158

Update version to 9.5.2

See merge request gitlab-org/gitlab-shell!170

pre-receive: Fix undefined local variable error

Closes #108

See merge request gitlab-org/gitlab-shell!169

This was broken during the refactor in c658360e.