[PATCH 3/3] git-rebase.txt: document --keep-base option

[Denton Liu <liu.denton@gmail.com>]

Document the --keep-base rebase option.

While we're at it, change an instance of "merge-base" to "merge base",
which is the consistent spelling.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
---
 Documentation/git-rebase.txt | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 6363d674b7..780d381667 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -8,8 +8,8 @@ git-rebase - Reapply commits on top of another base tip
 SYNOPSIS
 --------
 [verse]
-'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>]
-	[<upstream> [<branch>]]
+'git rebase' [-i | --interactive] [<options>] [--exec <cmd>]
+	[--onto <newbase> | --keep-base] [<upstream> [<branch>]]
 'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>]
 	--root [<branch>]
 'git rebase' --continue | --skip | --abort | --quit | --edit-todo | --show-current-patch
@@ -217,6 +217,12 @@ As a special case, you may use "A\...B" as a shortcut for the
 merge base of A and B if there is exactly one merge base. You can
 leave out at most one of A and B, in which case it defaults to HEAD.
 
+--keep-base::
+	Set the starting point at which to create the new commits to the
+	merge base of <upstream> <branch>. Running
+	'git rebase --keep-base <upstream> <branch>' is equivalent to
+	running 'git rebase --onto <upstream>... <upstream>'.
+
 <upstream>::
 	Upstream branch to compare against.  May be any valid commit,
 	not just an existing branch name. Defaults to the configured
@@ -863,7 +869,7 @@ NOTE: While an "easy case recovery" sometimes appears to be successful
       --interactive` will be **resurrected**!
 
 The idea is to manually tell 'git rebase' "where the old 'subsystem'
-ended and your 'topic' began", that is, what the old merge-base
+ended and your 'topic' began", that is, what the old merge base
 between them was.  You will have to find a way to name the last commit
 of the old 'subsystem', for example:
 
-- 
2.21.0.512.g57bf1b23e1