docs(projects): fix file deletion docs

VeLKerr · max-wittig · commit 1c4f1c401852 · 2019-12-16T10:32:29.000+01:00
The function `file.delete()` requires `branch` argument in addition to `commit_message`.
diff --git a/docs/gl_objects/projects.rst b/docs/gl_objects/projects.rst
@@ -368,7 +368,7 @@ encoded text::
 
 Delete a file::
 
-    f.delete(commit_message='Delete testfile')
+    f.delete(commit_message='Delete testfile', branch='master')
 
 Get file blame::
 
