Add deprecation notice to statcache.
diff --git a/Doc/lib/libstatcache.tex b/Doc/lib/libstatcache.tex
index 572e8b1..3e7aaa3 100644
--- a/Doc/lib/libstatcache.tex
+++ b/Doc/lib/libstatcache.tex
@@ -5,6 +5,12 @@
\sectionauthor{Moshe Zadka}{moshez@zadka.site.co.il}
\modulesynopsis{Stat files, and remember results.}
+
+\deprecated{2.2}{Use \function{\refmodule{os}.stat()} directly instead
+of using the cache; the cache introduces a very high level of
+fragility in applications using it and complicates application code
+with the addition of cache management support.}
+
The \module{statcache} module provides a simple optimization to
\function{os.stat()}: remembering the values of previous invocations.