Patch #781126: Fix markup for add_fallback. Will backport to 2.3.
diff --git a/Doc/lib/libgettext.tex b/Doc/lib/libgettext.tex
index 043fa58..ace719f 100644
--- a/Doc/lib/libgettext.tex
+++ b/Doc/lib/libgettext.tex
@@ -216,7 +216,7 @@
override this method to parse your format.
\end{methoddesc}
-\begin{methoddesc}{NullTranslations}{add_fallback}{fallback}
+\begin{methoddesc}[NullTranslations]{add_fallback}{fallback}
Add \var{fallback} as the fallback object for the current translation
object. A translation object should consult the fallback if it cannot
provide a translation for a given message.