Request for Documentation: Create Forum post: Mattermost GitLab plugin vs. Mattermost integration in GitLab

[matterdoc]

Mattermost user justine.geffen from https://community-daily.mattermost.com has requested the following be documented:

Hello, I have a question regarding mattermost integration in gitlab vs [mattermost-plugin-gitlab](https://github.com/mattermost/mattermost-plugin-gitlab).
I have setup a local Gitlab community edition instance, which comes with integrated mattermost server. Gitlab also includes a built-in integration with Mattermost. Using incoming webhooks it allows Gitlab to e.g. notify about merge requests and ci job failures, etc.

Does [mattermost-plugin-gitlab](https://github.com/mattermost/mattermost-plugin-gitlab) offer more features than the already built-in functionality?
Can I run both in parallel?

See the original post here.

This issue was generated from Mattermost using the Doc Up plugin.

[reimer-atb]

@justinegeffen I had also created an issue in mattermost-plugin-gitlab repository.

[cwarnermm]

@aaronrothschild - We could use your help with this one. Are you open to drafting a content update?