docs: Improve the example that illustrates git-notes path names

The existing git-notes doc says:

> Permitted pathnames have the form ab/cd/ef/…​/abcdef…​: a sequence of
> directory names of two hexadecimal digits each followed by a filename
> with the rest of the object ID.

Even though the text says that the filename has the rest of the object ID,
I felt the need to check this, since the example gives the impression that
the filename is the entire object ID (a schema which is quite prevalent).

The new example makes it clear that the filename has only the rest of the
object ID, and not the entire object ID.

Signed-off-by: Noam Yorav-Raphael <[email protected]>

Author: noamraph

Documentation/git-notes.txt

@@ -223,7 +223,7 @@ are taken from notes refs.  A notes ref is usually a branch which
 contains "files" whose paths are the object names for the objects
 they describe, with some directory separators included for performance
 reasons footnote:[Permitted pathnames have the form
-'ab'`/`'cd'`/`'ef'`/`'...'`/`'abcdef...': a sequence of directory
+'12'`/`'34'`/`'56'`/`'...'`/`'789abc...': a sequence of directory
 names of two hexadecimal digits each followed by a filename with the
 rest of the object ID.].