Clarifying special case when creating a branch for migration (MetOffice#527)

Author: mo-lottieturner

source/WorkingPractices/gh_authorisation.rst

@@ -132,12 +132,12 @@ Then configure git locally at the command line:
 
     # create a configuration for allowed signers - this only needs to be done once.
     # create a configuration location for git
-    mkdir ~/.config/git`
-    # Then< substituting the email you used for the git config (above)
+    mkdir ~/.config/git
+    # Then substituting the email you used for the git config (above)
     # and your own ssh key (noting that this is linking to the `.pub` public part)
     echo "<email_address> $(cat ~/.ssh/<correct-ssh-key.pub>)" > ~/.config/git/allowed-signers
 
-    # This assumes a global configuration>
+    # This assumes a global configuration
     # Substitute `git config` for `git config --global` for by-repository configuration
     git config --global gpg.format ssh
     # Noting that the </path/to/key> is to the private part, and must match
@@ -161,7 +161,7 @@ a branch on Github (on a personal fork), then browse to the commit list.
 
 There should be a green `Verified` label beside each signed commit.
 
-..tip ::
+.. tip::
 
     One can retrospectively change commits in a repository, if required, with
     `git rebase -i HEAD~<N>` # where <N> is the number of commits back to change

source/WorkingPractices/gh_dev_init.rst

@@ -192,6 +192,14 @@ To create a branch and switch to it from the command line, the syntax is,
             git branch <branch_name> <start_point>
             git switch <branch_name>
 
+.. tip::
+
+    If you're creating a branch to use to
+    :ref:`migrate an fcm branch <branch_migration>` across to git, you'll need
+    to branch from either the git_migration tag or the hash that matches your
+    fcm branch origin. This can be done by filling in `<start_point>` in the
+    commands above.
+
 Developing a Change
 -------------------