Document warn_explicit().
diff --git a/Doc/lib/libwarnings.tex b/Doc/lib/libwarnings.tex
index 051c79d..21d0bcf 100644
--- a/Doc/lib/libwarnings.tex
+++ b/Doc/lib/libwarnings.tex
@@ -161,6 +161,16 @@
the latter would defeat the purpose of the warning message).
\end{funcdesc}
+\begin{funcdesc}{warn_explicit}{message, category, filename,
+ lineno\optional{, module\optional{, registry}}}
+This is a low-level interface to the functionality of
+\function{warn()}, passing in explicitly the message, category,
+filename and line number, and optionally the module name and the
+registry (which should be the \code{__warningregistry__} dictionary of
+the module). The module name defaults to the filename with \code{.py}
+stripped; if no registry is passed, the warning is never suppressed.
+\end{funcdesc}
+
\begin{funcdesc}{showwarning}{message, category, filename,
lineno\optional{, file}}
Write a warning to a file. The default implementation calls