[libxml2] Add myself to maintainers

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 343bf0d39bf661ac5a3ae2e9251f489c5d1eb471
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sun Jan 16 13:52:21 2022 +0100

    Add myself to maintainers
    
    Fixes #319.

 libxml2.doap | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/libxml2.doap b/libxml2.doap
index 7b24b331..272ea5f9 100644
--- a/libxml2.doap
+++ b/libxml2.doap
@@ -16,4 +16,10 @@
       <gnome:userid>veillard</gnome:userid>
     </foaf:Person>
   </maintainer>
+  <maintainer>
+    <foaf:Person>
+      <foaf:name>Nick Wellnhofer</foaf:name>
+      <gnome:userid>nwellnhof</gnome:userid>
+    </foaf:Person>
+  </maintainer>
 </Project>