runtime(doc): update doc for :horizontal

Revert the documentation for :horizontal from commit
0c3e57b403e0e3a1fefc because :horizontal cannot be shortened to :ho

closes: #16362

Signed-off-by: h-east <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index 5b844fb..512e284 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -1386,7 +1386,7 @@
 |:highlight|	:hi[ghlight]	specify highlighting methods
 |:hide|		:hid[e]		hide current buffer for a command
 |:history|	:his[tory]	print a history list
-|:horizontal|	:ho[rizontal]	following window command work horizontally
+|:horizontal|	:hor[izontal]	following window command work horizontally
 |:insert|	:i[nsert]	insert text
 |:iabbrev|	:ia[bbrev]	like ":abbrev" but for Insert mode
 |:iabclear|	:iabc[lear]	like ":abclear" but for Insert mode