Fix 1988/litmaath/README.md + add alt code

There was no 'To build' or 'To run' section.

The alt code is that which the judges suggested to try and understand
the code a bit more. As it was fun output and it seems instructive I
decided to add it as an alt version.

Updated .gitignore.

1988/litmaath/Makefile

@@ -111,8 +111,8 @@ OBJ= ${PROG}.o
 DATA=
 TARGET= ${PROG}
 #
-ALT_OBJ=
-ALT_TARGET=
+ALT_OBJ= ${PROG}.alt.o
+ALT_TARGET= ${PROG}.alt
 
 
 #################