doc: checkout: remove duplicate synopsis

It was added in [1]. I understand that the duplicate change was not
intentional and comes from an oversight.

Also, in explanation, there was only one section for two synopsis
entries.

Fix both problems by removing duplicate synopsis.

<paths> vs <pathspec> is resolved in next patch.

[1] Commit b59698a ("checkout doc: clarify command line args for "checkout paths" mode" 2017-10-11)

Signed-off-by: Alexandr Miloslavskiy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: SyntevoAlex

Documentation/git-checkout.txt

@@ -13,7 +13,6 @@ SYNOPSIS
 'git checkout' [-q] [-f] [-m] [--detach] <commit>
 'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]
 'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
-'git checkout' [<tree-ish>] [--] <pathspec>...
 'git checkout' (-p|--patch) [<tree-ish>] [--] [<paths>...]
 
 DESCRIPTION
@@ -79,7 +78,7 @@ be used to detach `HEAD` at the tip of the branch (`git checkout
 +
 Omitting `<branch>` detaches `HEAD` at the tip of the current branch.
 
-'git checkout' [<tree-ish>] [--] <pathspec>...::
+'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...::
 
 	Overwrite paths in the working tree by replacing with the
 	contents in the index or in the `<tree-ish>` (most often a