[gtk-doc] rebase: add the option help text back in

[Stefan Sauer <stefkost src gnome org>]

commit 1147f730f4de0dee71ff5315d11a09600caea72d
Author: Stefan Sauer <ensonic users sf net>
Date:   Wed Apr 5 20:13:22 2017 +0200

    rebase: add the option help text back in
    
    This was lost in the porting step.

 gtkdoc-rebase.in |   23 ++++++++++++++++-------
 1 files changed, 16 insertions(+), 7 deletions(-)
---
diff --git a/gtkdoc-rebase.in b/gtkdoc-rebase.in
index 0f37012..4ab9d81 100755
--- a/gtkdoc-rebase.in
+++ b/gtkdoc-rebase.in
@@ -31,14 +31,23 @@ if __name__ == '__main__':
     parser = argparse.ArgumentParser(
         description='gtkdoc-rebase version %s - rewrite links in html docs' % config.version)
     parser.add_argument('--version', action='version', version=config.version)
-    parser.add_argument('--html-dir', dest='html_dir', default='')
-    parser.add_argument('--other-dir', dest='other_dir', default=[], action='append')
-    parser.add_argument('--dest-dir', dest='dest_dir', default='')
-    parser.add_argument('--aggressive', action='store_true', default=False)
-    parser.add_argument('--verbose', action='store_true', default=False)
+    parser.add_argument('--html-dir', dest='html_dir', default='',
+                        help='The directory which contains the installed HTML')
+    parser.add_argument('--other-dir', dest='other_dir', default=[], action='append',
+                        help='Directories to recursively scan for indices (*.devhelp2).'
+                        'May be used more than once for multiple directories.')
+    parser.add_argument('--dest-dir', dest='dest_dir', default='',
+                        help='Staging area virtual root, this prefix will be removed'
+                        'from HTML_DIR for relative link calculation.')
+    parser.add_argument('--aggressive', action='store_true', default=False,
+                        help='Rebase links to all files that are under a directory matching a package name.')
+    parser.add_argument('--verbose', action='store_true', default=False,
+                        help='Print extra output while processing')
     group = parser.add_mutually_exclusive_group()
-    group.add_argument('--online', action='store_true', default=False)
-    group.add_argument('--relative', action='store_true', default=False)
+    group.add_argument('--online', action='store_true', default=False,
+                       help='Prefer cross-references to online documents')
+    group.add_argument('--relative', action='store_true', default=False,
+                       help='Prefer relative cross-references')
 
     options = parser.parse_args()