Add 1994/horton/try scripts and article cited

The try.sh and try.alt.sh scripts correspond to the original entry and
the alt code (which is enhanced).

The PDF files might need a bit more explaining. The author wrote an
article in 'The USENIX Association Newsletter ;login: September /
October 1992 Vol. 17, No. 5' (the exact title from the PDF) called
'Using GraphTab'. I found the full newsletter in the Internet Wayback
Machine which is now added to the repo (okay: the newsletter as a PDF is
added to the repo, not the Internet Wayback Machine :-) ). But the pages
cited are 28-31 so I extracted (with macOS Preview app: File -> Print
option) the specific pages so one need not look at the full newsletter
if they do not wish to. It felt better to have the PDF rather than
images as it's easier to deal with what the right size is: the size is
there and one can zoom in or out as they see fit (whereas with images
different resolutions make it easier or harder to see what is in them).

1994/horton/README.md

@@ -17,13 +17,7 @@ make all
 ## Try:
 
 ```sh
-./horton 3 2 1 0
-```
-
-Also try:
-
-```sh
-./gtface  < gtface.data
+./try.sh
 ```
 
 
@@ -46,14 +40,25 @@ make alt
 ./horton.alt A B C D
 ```
 
-Where A, B, C and D are like with `horton`.
+Where A, B, C and D are numbers like with `horton`.
+
+
+### Alternate try:
+
+```sh
+./try.alt.sh
+```
 
 
 ## Judges' remarks:
 
 Try to figure out how this program prints, for a given slope, the
 right character.  And for extra credit, try to figure out which
-character is at the bottom on this hint file.  :-)
+character is at the bottom of this hint file.  :-)
+
+You might be interested in the author's article that they cite towards the end
+of their remarks, included as PDF files for your convenience, the full
+newsletter and a PDF file of just the pages cited.
 
 
 ## Author's remarks:
@@ -62,6 +67,7 @@ Run it with any 4 numeric arguments, e.g. `./horton 3 2 1 0`.  Play with the
 numbers to get a pleasing result, or use it for your high school algebra
 class.
 
+
 ### SPOILER:
 
 As should be obvious from 20 feet away, the program is a cubic plotter.
@@ -79,10 +85,10 @@ make gtface
 ./gtface < gtface.data
 ```
 
-For more information, see
+For more information, see my article
 
-Using GraphTab; USENIX ;login:
-Sept/Oct 1992; Pages 28-31
+[Using GraphTab; USENIX ;login: Sept/Oct 1992](login_sept92.pdf), [pages
+28-31](login_sept92-pp28-31.pdf).
 
 ```