alice: README: Support earlier versions of git by getting branch name without --show-current

Author: pdxjohnny

entities/alice/README.rst

@@ -115,7 +115,7 @@ Create a new git repo and add some contents
     $ echo 'print("Hello World")' > test.py
     $ git add test.py
     $ git commit -sam 'Initial Commit'
-    $ git push --set-upstream origin master
+    $ git push --set-upstream origin $(git branch -r | sed -e 's/.*\///')
 
 Ask Alice: please contribute recommended community standards to the repo