Add -lm to 2000/briddlebane/Makefile

The entry would not compile in the systems that require the explicit use
of -lm for libm. Two example systems are fedora and Rocky linux.

I also fixed a couple typos in README.md.

2000/briddlebane/Makefile

@@ -74,7 +74,7 @@ CFLAGS= ${CSTD} ${CWARN} ${ARCH} ${CDEFINE} ${CINCLUDE} ${OPT}
 
 # Libraries needed to build
 #
-LIBS=
+LIBS= -lm
 
 # C compiler to use
 #