Set master as the default branch for push and pull

The command git pull have always given me the following boring message:

$ git pull
You asked me to pull without telling me which branch you
want to merge with, and 'branch.active_model.merge' in
your configuration file does not tell me, either. Please
specify which branch you want to use on the command line and
try again (e.g. 'git pull <repository> <refspec>').
See git-pull(1) for details.

If you often merge with the same branch, you may want to
use something like the following in your configuration file:
    [branch "branch_name"]
    remote = <nickname>
    merge = <remote-ref>

    [remote "<nickname>"]
    url = <url>
    fetch = <refspec>

See git-config(1) for details.

To solve this I added some configurations to git's repo config file by the following commands:

$ git config branch.master.merge refs/heads/master

This command tells git that when you're on the master branch, the default remote is origin

$ git config branch.master.remote origin

This command tells git that when you're pulling from the master branch, it must use the default remote specified with the previous command