Fix #gl/-docsteam typo in contribute docs

Community Contribution Docs > Documentation says to mention @gl/-docsteam in a comment after making MR.

@gl/-docsteam does not exist and mentioning this will not notify gl-docsteam or work as intended.

@gl/-docsteam is a typo - it should be @gl-docsteam (without the /)

fixes #4015 (closed)