added a few missing \versionadded{2.3} tags
diff --git a/Doc/lib/libstringprep.tex b/Doc/lib/libstringprep.tex
index 3492d02..2614314 100644
--- a/Doc/lib/libstringprep.tex
+++ b/Doc/lib/libstringprep.tex
@@ -6,6 +6,8 @@
\moduleauthor{Martin v. L\"owis}{martin@v.loewis.de}
\sectionauthor{Martin v. L\"owis}{martin@v.loewis.de}
+\versionadded{2.3}
+
When identifying things (such as host names) in the internet, it is
often necessary to compare such identifications for
``equality''. Exactly how this comparison is executed may depend on