branch: improve documentation and naming of create_branch() parameters

The documentation for 'create_branch()' was incomplete as it didn't say
what certain parameters were used for. Further a parameter name wasn't
very communicative.

So, add missing documentation for the sake of completeness and easy
reference. Also, rename the concerned parameter to make its name more
communicative.

Signed-off-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

branch.c

@@ -228,7 +228,7 @@ N_("\n"
 "\"git push -u\" to set the upstream config as you push.");
 
 void create_branch(const char *name, const char *start_name,
-		   int force, int reflog, int clobber_head,
+		   int force, int reflog, int clobber_head_ok,
 		   int quiet, enum branch_track track)
 {
 	struct commit *commit;
@@ -244,7 +244,7 @@ void create_branch(const char *name, const char *start_name,
 
 	if (validate_new_branchname(name, &ref, force,
 				    track == BRANCH_TRACK_OVERRIDE ||
-				    clobber_head)) {
+				    clobber_head_ok)) {
 		if (!force)
 			dont_change_ref = 1;
 		else

branch.h

@@ -15,12 +15,17 @@
  *
  *   - reflog creates a reflog for the branch
  *
+ *   - clobber_head_ok allows the currently checked out (hence existing)
+ *     branch to be overwritten; without 'force', it has no effect.
+ *
+ *   - quiet suppresses tracking information
+ *
  *   - track causes the new branch to be configured to merge the remote branch
  *     that start_name is a tracking branch for (if any).
  */
 void create_branch(const char *name, const char *start_name,
 		   int force, int reflog,
-		   int clobber_head, int quiet, enum branch_track track);
+		   int clobber_head_ok, int quiet, enum branch_track track);
 
 /*
  * Validates that the requested branch may be created, returning the