Documentation/howto/maintain-git.txt: fix Meta/redo-jch.sh invocation

The Meta/redo-jch.sh script is generated a few lines earlier by running:

    $ Meta/Reintegrate master..seen >Meta/redo-jch.sh

But the resulting script is not necessarily executable. Later mentions
of this script invoke it with sh (instead of directly), but this one is
an odd one out.

Update the documentation to invoke the Meta/redo-jch.sh script with sh
in case the maintainer has not made the script executable.

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

Documentation/howto/maintain-git.txt

@@ -256,7 +256,7 @@ by doing the following:
    merged to 'next', add it at the end of the list.  Then:
 
      $ git checkout -B jch master
-     $ Meta/redo-jch.sh -c1
+     $ sh Meta/redo-jch.sh -c1
 
    to rebuild the 'jch' branch from scratch.  "-c1" tells the script
    to stop merging at the first line that begins with '###'