Updates to 1990/tbr - alt code

Properly document the fact that there is alt code. This involved a note
about the fixes in 2023 as the alt code had to have fixes applied too
and it was referred to in the description of it (that was not referred
to as alt code).

I have not yet checked the README.md file for formatting or typo issues.

1990/tbr/README.md

@@ -13,6 +13,27 @@ US
 make all
 ```
 
+There is an [alternate version](#alternate-code) to this program.
+
+
+### A note about the fixes of this entry in 2023:
+
+In 2023 it was noticed that in some systems like macOS there was confusing
+output due to a warning at runtime that was interspersed with the output of the
+program. For instance it would show:
+
+```sh
+$ ./tbr
+$ warning: this program uses gets(), which is unsafe.
+```
+
+which kind of hid the prompt. Thus the entry was changed to use `fgets(3)` which
+is referred to later in this file.
+
+Also `exit(3)` returns void but the entry was using it in a binary expression so
+this entry would not compile in modern systems. This fix is also referred to
+below, in the [alternate version](#alternate-code) section.
+
 
 ## To use:
 
@@ -54,14 +75,7 @@ The authors include a section called [BUGS](#bugs) that, because they were
 documented, are not considered bugs as such in the context of the contest.
 
 
-## Judges' remarks:
-
-This program touches on a well known Unix utility, the 6th edition Bourne Shell
-(`/bin/sh`), whose original source was considered to be extremely obfuscated by
-many people (although Steve Bourne might disagree). Did you know that the Bourne
-Shell source was a major inspiration for the formation of the IOCCC back in
-1984?
-
+## Alternate code:
 
 The authors supplied us with a slightly smaller unformatted version
 of the program which we include below:
@@ -79,8 +93,32 @@ r(o,0)D o)D*f):4,wait(0):(o?dup2(*f,0)D*f)D o):*i?1 D
 e(x){x<0?write(2,"?\n$ "-x/4,2),x+1||(exit(1),0):5;}
 ```
 
-It has the `exit()` returns void fix as well as the `gets()` to `fgets()` fix
-applied to it to make it functionally equivalent like the authors intended.
+and in the [alternate source](tbr.alt.c). It has the `exit()` returns void fix
+as well as the `gets()` to `fgets()` fix applied to it to make it functionally
+equivalent like the authors intended.
+
+
+### Alternate build:
+
+```sh
+make alt
+```
+
+
+### Alternate use:
+
+```sh
+./tbr.alt
+```
+
+
+## Judges' remarks:
+
+This program touches on a well known Unix utility, the 6th edition Bourne Shell
+(`/bin/sh`), whose original source was considered to be extremely obfuscated by
+many people (although Steve Bourne might disagree). Did you know that the Bourne
+Shell source was a major inspiration for the formation of the IOCCC back in
+1984?
 
 
 ## Authors' remarks:

thanks-for-fixes.md

@@ -1000,8 +1000,10 @@ like the same as the original.
 Additionally, Cody fixed the shortened version provided by the author in the
 same way as the original entry, first the compile fix and then later on making
 it look more like the original by redefining `exit` and also redefining `gets()`
-to be `fgets()` in the same way that the original entry is. This way the alt
-version is equivalent in function, like the author intended, but more compact.
+to be `fgets()` in the same way that the original entry is. This way the [alt
+version](1990/tbr/README.md#alternate-code) is equivalent in function, like the
+author intended, but more compact.
+
 
 ## [1990/theorem](1990/theorem/theorem.c) ([README.md](1990/theorem/README.md]))