Documentation: talk about pathspec in bisect.

Also work-around asciidoc manpage trouble that does not seem to
allow more than one line in the SYNOPSIS section.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-bisect.txt

@@ -8,16 +8,21 @@ git-bisect - Find the change that introduced a bug
 
 SYNOPSIS
 --------
- 'git bisect' start
- 'git bisect' bad <rev>
- 'git bisect' good <rev>
- 'git bisect' reset [<branch>]
- 'git bisect' visualize
- 'git bisect' replay <logfile>
- 'git bisect' log
+'git bisect' <subcommand> <options> 
 
 DESCRIPTION
 -----------
+The command takes various subcommands, and different options
+depending on the subcommand:
+
+ git bisect start [<paths>...]
+ git bisect bad <rev>
+ git bisect good <rev>
+ git bisect reset [<branch>]
+ git bisect visualize
+ git bisect replay <logfile>
+ git bisect log
+
 This command uses 'git-rev-list --bisect' option to help drive
 the binary search process to find which change introduced a bug,
 given an old "good" commit object name and a later "bad" commit
@@ -26,9 +31,9 @@ object name.
 The way you use it is:
 
 ------------------------------------------------
-git bisect start
-git bisect bad			# Current version is bad
-git bisect good v2.6.13-rc2	# v2.6.13-rc2 was the last version
+$ git bisect start
+$ git bisect bad			# Current version is bad
+$ git bisect good v2.6.13-rc2		# v2.6.13-rc2 was the last version
 					# tested that was good
 ------------------------------------------------
 
@@ -43,7 +48,7 @@ and check out the state in the middle. Now, compile that kernel, and boot
 it. Now, let's say that this booted kernel works fine, then just do
 
 ------------------------------------------------
-git bisect good			# this one is good
+$ git bisect good			# this one is good
 ------------------------------------------------
 
 which will now say
@@ -62,7 +67,7 @@ kernel rev in "refs/bisect/bad".
 Oh, and then after you want to reset to the original head, do a
 
 ------------------------------------------------
-git bisect reset
+$ git bisect reset
 ------------------------------------------------
 
 to get back to the master branch, instead of being in one of the bisection
@@ -72,7 +77,9 @@ not using some old bisection branch).
 
 During the bisection process, you can say
 
-	git bisect visualize
+------------
+$ git bisect visualize
+------------
 
 to see the currently remaining suspects in `gitk`.
 
@@ -80,11 +87,40 @@ The good/bad input is logged, and `git bisect
 log` shows what you have done so far.  You can truncate its
 output somewhere and save it in a file, and run
 
-	git bisect replay that-file
+------------
+$ git bisect replay that-file
+------------
 
 if you find later you made a mistake telling good/bad about a
 revision.
 
+If in a middle of bisect session, you know what the bisect
+suggested to try next is not a good one to test (e.g. the change
+the commit introduces is known not to work in your environment
+and you know it does not have anything to do with the bug you
+are chasing), you may want to find a near-by commit and try that
+instead.  It goes something like this:
+
+------------
+$ git bisect good/bad			# previous round was good/bad.
+Bisecting: 337 revisions left to test after this
+$ git bisect visualize			# oops, that is uninteresting.
+$ git reset --hard HEAD~3		# try 3 revs before what
+					# was suggested
+------------
+
+Then compile and test the one you chose to try.  After that,
+tell bisect what the result was as usual.
+
+You can further cut down the number of trials if you know what
+part of the tree is involved in the problem you are tracking
+down, by giving paths parameters when you say `bisect start`,
+like this:
+
+------------
+$ git bisect start arch/i386 include/asm-i386
+------------
+
 
 Author
 ------