Minor fixes in 1990/tbr

Remove note in Makefile that this entry does not compile with modern
compilers. I fixed that quite a while ago but neglected to remove the
message.

The README.md I changed 'i/o' to 'I/O' and I removed the reference to
the original version with gets() from the archive as it's now in the
tbr.orig.c file.

1990/tbr/Makefile

@@ -130,7 +130,6 @@ all: data ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
-	@echo "NOTE: This entry might not compile when using modern compilers."
 	${CC} ${CFLAGS} $< -o $@ ${LDFLAGS}
 
 # alternative executable

1990/tbr/README.md

@@ -13,10 +13,6 @@ US
 make all
 ```
 
-For the original version with `gets()` see the [archive
-tarball](/archive/archive-1990.tar.bz2).
-
-
 ## To run:
 
 ```sh
@@ -77,7 +73,7 @@ applied.
 
 ## Author's remarks:
 
-This program is a rudimentary shell. It does i/o redirection, pipes
+This program is a rudimentary shell. It does I/O redirection, pipes
 and cd. It flags errors on failed `chdir()`, `open()`, `creat()`,
 `execvp()`, `fork()` and a few syntax errors.