Refactor authorization_for_merge_requests.md

doc/user/project/merge_requests/authorization_for_merge_requests.md

 # Authorization for Merge requests
 
-There are two main ways to have a merge request flow with GitLab: working with protected branches in a single repository, or working with forks of an authoritative project.
+There are two main ways to have a merge request flow with GitLab:
+
+1. Working with [protected branches] in a single repository.
+1. Working with forks of an authoritative project.
 
 ## Protected branch flow
 
 With the protected branch flow everybody works within the same GitLab project.
 
-The project maintainers get Master access and the regular developers get Developer access.
+The project maintainers get Master access and the regular developers get
+Developer access.
 
 The maintainers mark the authoritative branches as 'Protected'.
 
-The developers push feature branches to the project and create merge requests to have their feature branches reviewed and merged into one of the protected branches.
+The developers push feature branches to the project and create merge requests
+to have their feature branches reviewed and merged into one of the protected
+branches.
 
-Only users with Master access can merge changes into a protected branch.
+By default, only users with Master access can merge changes into a protected
+branch.
 
-### Advantages
+**Advantages**
 
-- fewer projects means less clutter
-- developers need to consider only one remote repository
+- Fewer projects means less clutter.
+- Developers need to consider only one remote repository.
 
-### Disadvantages
+**Disadvantages**
 
-- manual setup of protected branch required for each new project
+- Manual setup of protected branch required for each new project
 
 ## Forking workflow
 
-With the forking workflow the maintainers get Master access and the regular developers get Reporter access to the authoritative repository, which prohibits them from pushing any changes to it.
+With the forking workflow the maintainers get Master access and the regular
+developers get Reporter access to the authoritative repository, which prohibits
+them from pushing any changes to it.
+
+Developers create forks of the authoritative project and push their feature
+branches to their own forks.
 
-Developers create forks of the authoritative project and push their feature branches to their own forks.
+To get their changes into master they need to create a merge request across
+forks.
 
-To get their changes into master they need to create a merge request across forks.
+**Advantages**
 
-### Advantages
+- In an appropriately configured GitLab group, new projects automatically get
+  the required access restrictions for regular developers: fewer manual steps
+  to configure authorization for new projects.
 
-- in an appropriately configured GitLab group, new projects automatically get the required access restrictions for regular developers: fewer manual steps to configure authorization for new projects
+**Disadvantages**
 
-### Disadvantages
+- The project need to keep their forks up to date, which requires more advanced
+  Git skills (managing multiple remotes).
 
-- the project need to keep their forks up to date, which requires more advanced Git skills (managing multiple remotes)
+[protected branches]: ../protected_branches.md