Help navigation bar: map to specific documentation based on source
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=214216) </details> <!--IssueSummary end--> Recently received feedback from a customer regarding our help navigation icon. Currently if you are on a project or merge request and you select the help icon on the nav bar it doesn't navigate to the corresponding help docs for that particular page (say I was on a project/repo or even group and selected help, it would be nice to automatically link to [Projects](https://docs.gitlab.com/ee/gitlab-basics/create-project.html) docs or if on a merge request and select help you are then navigated to the [merge request](https://docs.gitlab.com/ee/user/project/merge_requests/) docs, etc), instead it takes you to the general docs page and then from there if you wanted to do a search for related documentation it pulls up projects and leaves you confused and sad. ![Help_Section](/uploads/10389aca53d88761993ac36badbadc38/Help_Section.mov) Customer Requested: https://gitlab.my.salesforce.com/0014M00001lc8tJ
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