Added entries for difflib documentation.
diff --git a/Doc/Makefile.deps b/Doc/Makefile.deps
index 8a04e04..7a79996 100644
--- a/Doc/Makefile.deps
+++ b/Doc/Makefile.deps
@@ -54,6 +54,7 @@
 	../lib/libfpectl.tex \
 	../lib/libgc.tex \
 	../lib/libweakref.tex \
+	../lib/libdifflib.tex \
 	../lib/libdoctest.tex \
 	../lib/libtypes.tex \
 	../lib/libtraceback.tex \
diff --git a/Doc/lib/lib.tex b/Doc/lib/lib.tex
index 58e011f..5dde036 100644
--- a/Doc/lib/lib.tex
+++ b/Doc/lib/lib.tex
@@ -103,6 +103,7 @@
 \input{libstring}
 \input{libre}
 \input{libstruct}
+\input{libdifflib}
 \input{libfpformat}
 \input{libstringio}
 \input{libcodecs}