Merge branch 'feature/ci/new-default-branch' into 'master'

Update release doc for branch creation

See merge request frama-c/frama-c!2502

doc/release/branch.tex

@@ -21,9 +21,24 @@ $\rightarrow$ Repository $\rightarrow$ Protected Branches.
 
 \section{Creating the branch}
 
-Create the branch \texttt{stable/release} where \texttt{release} is the
-element name.
-
+Create the branch \texttt{stable/release}, where \texttt{release} is the
+element name, using the \texttt{frama-ci} tool:
+\begin{enumerate}
+\item Install \texttt{frama-ci} tools:
+\begin{shell}
+opam pin add frama-ci-tools git@git.frama-c.com:frama-c/Frama-CI.git
+\end{shell}
+\item Create an API token for gitlab, in your gitlab profile settings.
+\item Run the command
+\begin{shell}
+frama-ci-create-branch --token=\$TOKEN \
+--new-branch=stable/release --default-branch
+\end{shell}
+This command creates a branch \texttt{stable/release} for frama-c and for
+each plugin tested by the CI — and configures the CI to use these branches
+by default when testing fixes for the release.
+These branches are directly created on the gitlab server.
+\end{enumerate}
 What can be committed in this branch must follow the release schedule,
 and go through Merge-requests. Everything else should go in \texttt{master},
 which can then be reset to standard-level protection (Developers + Masters