Document MAKEPKG_LIBRARY in makepkg(8)

doc/makepkg.8.asciidoc

@@ -233,6 +233,9 @@ before building.
 
 Environment Variables
 ---------------------
+**MAKEPKG_LIBRARY**="/path/to/directory"::
+	Use an alternative libmakepkg path instead of the {libmakepkgdir} default.
+
 **PACMAN**::
 	The command that will be used to check for missing dependencies and to
 	install and remove packages. Pacman's '-Qq', '-Rns', '-S', '-T', and '-U'

doc/meson.build

@@ -35,6 +35,7 @@ asciidoc_opts = [
  '-a', 'sysconfdir=@0@'.format(SYSCONFDIR),
  '-a', 'datarootdir=@0@'.format(DATAROOTDIR),
  '-a', 'rootdir=@0@'.format(ROOTDIR),
+ '-a', 'libmakepkgdir=@0@'.format(LIBMAKEPKGDIR),
 ]
 
 html_targets = []