docs overhaul: move git cli instructions to a separate file

contributing-guides/git-terminal.md

@@ -0,0 +1,24 @@
+Most people submit pull requests to the tldr project using GitHub's web interface.
+
+If you prefer, you can do most of the process using the command line instead:
+
+- fork the repository on the github web interface
+
+- clone your fork locally:  
+  `git clone https://github.com/{{your_username}}/tldr.git && cd tldr`
+
+- create a feature branch, e.g. named after the command you plan to edit:  
+  `git checkout -b {{branch_name}}`
+
+- make your changes (edit existing files or create a new one)
+
+- commit the changes:  
+  `git commit --all -m "{{commit_message}}"`
+
+- push to your fork:  
+  `git push origin {{branch_name}}`
+
+- go to the github page for your fork and click the green pull request button.
+
+Please send only related changes in the same pull request.
+Typically a pull request will include changes in a single file.