fix/enhance start-using-git doc

What does this MR do?

Fixes and enhances the Start Using Git user documentation

Why was this MR needed?

To fix grammatical errors, clarify statements, and add more descriptions. This enhances the documentation.

Does this MR meet the acceptance criteria?

It should. It's just documentation.

What are the relevant issue numbers?

None.

Suggested approvers

I suggest the following approvers: @winh @leipert @iamphill @timzallmann @rymai @leipert @timzallmann @axil Thanks in advance!