Add definition for branch

[jade-abc]

Added a definition for branch. Is it worth clarifying that branches tend to be merged back into main repositories?

[rkratky]

Is it worth clarifying that branches tend to be merged back into main repositories?

Good point. Worth adding.

[rkratky]

Thank you, @jade-abc. Please, add the rest of the definition as you suggested in your initial comment.

[s-makin]

Thank you, @jade-abc. Please, add the rest of the definition as you suggested in your initial comment.

It's been quite a while since this was worked. I suggest we merge it as-is, and if they come back can submit a follow-up PR.