Mention which branch to use for patches/PRs
Even if it's set as the default branch on github, it's probably better to
mention that explicitly.
diff --git a/README.rst b/README.rst
index 0d9b614..90cec14 100644
--- a/README.rst
+++ b/README.rst
@@ -150,7 +150,8 @@
`start a discussion <https://tls.mbed.org/discussions>`_ around a feature
idea or a bug.
#. Fork the `mbed TLS repository on Github <https://github.com/ARMmbed/mbedtls>`_
- to start making your changes.
+ to start making your changes. As a general rule, you should use the
+ "development" branch as a basis.
#. Write a test which shows that the bug was fixed or that the feature works
as expected.
#. Send a pull request and bug us until it gets merged and published. We will