Update LFS docs with File Locking section

doc/workflow/lfs/manage_large_binaries_with_git_lfs.md

@@ -83,6 +83,71 @@ that are on the remote repository, eg. from branch `master`:
 git lfs fetch master
 ```
 
+## File Locking
+
+The first thing to do before using File Locking is to tell Git LFS which
+kind of files are lockable. The following command will store PNG files
+in LFS and flag them as lockable:
+
+```bash
+git lfs track "*.png" --lockable
+```
+
+After executing the above command a file named `.gitattributes` will be
+created or updated with the following content:
+
+```bash
+*.png filter=lfs diff=lfs merge=lfs -text lockable
+```
+
+You can also register a file type as lockable without using LFS, in
+order to do that you can edit the `.gitattributes` file manually:
+
+```bash
+*.pdf lockable
+```
+
+After a file type has been registered as lockable, Git LFS will make
+them readonly on the file system automatically. This means you will
+need to lock the file before editing it.
+
+### Managing Locked Files
+
+Once you're ready to edit your file you need to lock it first:
+
+```bash
+git lfs lock images/banner.png
+Locked images/banner.png
+```
+
+This will register the file as locked in your name on the server:
+
+```bash
+git lfs locks
+images/banner.png  joe   ID:123
+```
+
+Once you have pushed your changes, you can unlock the file so others can
+also edit it:
+
+```bash
+git lfs unlock images/banner.png
+```
+
+You can also unlock by id:
+
+```bash
+git lfs unlock --id=123
+```
+
+If for some reason you need to unlock a file that was not locked by you,
+you can use the `--force` flag as long as you have a `master` access on
+the project:
+
+```bash
+git lfs unlock --id=123 --force
+```
+
 ## Troubleshooting
 
 ### error: Repository or object not found