docs/man/Makefile.am: typo fix in comments

Signed-off-by: Jim Klimov <jimklimov+nut@gmail.com>

Author: jimklimov

docs/man/Makefile.am

@@ -950,7 +950,7 @@ CLEANFILES = *-spellchecked .prep-src-docs *-prepped
 
 SUFFIXES = .txt-prepped .txt .html .1 .3 .5 .8
 
-# For builds with allowed installation of prebuild man pages, check that
+# For builds with allowed installation of prebuilt man pages, check that
 # they exist in sources (make would pull them automatically as a fallback
 # from failed lookup in build products). For builds that require rebuild
 # of man pages, abort with error if build product is missing.