Add entries for the doctest documentation.

Doc/Makefile.deps

@@ -54,6 +54,7 @@ LIBFILES= $(MANSTYLES) $(COMMONTEX) \
 	../lib/libfpectl.tex \
 	../lib/libgc.tex \
 	../lib/libweakref.tex \
+	../lib/libdoctest.tex \
 	../lib/libtypes.tex \
 	../lib/libtraceback.tex \
 	../lib/libpickle.tex \

Doc/lib/lib.tex

@@ -109,6 +109,7 @@ and how to embed it in other applications.
 \input{libunicodedata}
 
 \input{libmisc}			% Miscellaneous Services
+\input{libdoctest}
 \input{libmath}
 \input{libcmath}
 \input{librandom}