rev-list-options.txt: use correct directional reference

The descriptions of the options '--parents', '--children' and
'--graph' say "see 'History Simplification' below", although the
referred section is in fact above the description of these options.

Send readers in the right direction by saying "above" instead of
"below".

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: szeder

Documentation/rev-list-options.txt

@@ -630,12 +630,12 @@ endif::git-rev-list[]
 --parents::
 
 	Print also the parents of the commit (in the form "commit parent...").
-	Also enables parent rewriting, see 'History Simplification' below.
+	Also enables parent rewriting, see 'History Simplification' above.
 
 --children::
 
 	Print also the children of the commit (in the form "commit child...").
-	Also enables parent rewriting, see 'History Simplification' below.
+	Also enables parent rewriting, see 'History Simplification' above.
 
 ifdef::git-rev-list[]
 --timestamp::
@@ -679,7 +679,7 @@ you would get an output like this:
 	to be printed in between commits, in order for the graph history
 	to be drawn properly.
 +
-This enables parent rewriting, see 'History Simplification' below.
+This enables parent rewriting, see 'History Simplification' above.
 +
 This implies the '--topo-order' option by default, but the
 '--date-order' option may also be specified.