newlib-cygwin.git repository: Switching "master" to "main"

[Corinna Vinschen]

Hey folks,

In the light of recent discussions, and following other projects already
having done this step, we changed the name of the "master" branch in
the newlib-cygwin.git upstream repository to "main".

If you fetched from upstream in the last two days, you might already
have noticed that an "origin/main" branch suddenly showed up, but your
"master" branch still worked as before.

The reason is that we also added a symbolic reference upstream, so that
"origin/master" points to "origin/main".  Both "branches" are now
constantly kept in sync upstream.

Therefore, you can continue your work on "master" without disruption,
if you prefer to do so.

However, on the client side, the "master" and "main" branches are
treated as two distinct branches.  If you work on your local "main"
clone and commit a patch, it's not keeping your local "master" branch in
sync.  After pushing your change upstream, though, the upstream idea of
"main" and "master" is, again, the same.  After fetching from upstream,
the patch will show up in both tracking branches, "origin/main" as well
as "origin/master", so pulling on both local branches will show the same
tree.

Having said that.  Ideally you only use one of the branches locally
to avoid any confusion:

- If you prefer to work in "master", just continue to do so and don't
  create a local "main" branch tracking "origin/main".

- If you prefer to work in "main", checkout "origin/main" as "main" and
  delete your local "master" branch.


Have fun,
Corinna