Add guide for gitlab

[4xpl0r3r]

Summary:
Ref: OWASP/threat-dragon#965 and #82

This is to add the guide of settting of GitLab access

closes #81

[fdellwing]

From my testing it is actually enough to just use the api scope because it contains all permissions.

[jgadsden]

apologies for not reviewing this earlier @4xpl0r3r , lots of pieces to pick up after OWASP Lisbon conference :)
Could you delete the trailing space on line 34? It keeps lint happy

@fdellwing could you expand on your review? Are you saying that the scopes can be just api and do not have to be read_user read_repository write_repository profile read_api api

[jgadsden]

If you can add these words to the .wordlist.txt file that will keep the spellchecker happy:

• configs
• URI
• BaseURL

[fdellwing]

Are you saying that the scopes can be just api and do not have to be read_user read_repository write_repository profile read_api api

I was not able to get the integration to work with just read_user read_repository write_repository profile read_api, I needed to give api. And as api contains all other scopes, they can be omitted.