Update several year README.md files

Mostly added links.

1987/README.md

@@ -6,19 +6,21 @@ on how to compile the winner and how to run the winning program.
 Look at the winning source and try to figure how it does what it does!
 You may then wish to look at the Author's comments for even more details.
 
-The rules for 1987 suggested even more categories than in 1986.  Hints
-for what to do and not to do were also given in the rules.  For
-example, a simple excessive abuse of /lib/cpp was discouraged unless
-the abuse was unusual.  The mailboxes for the contest were moved from
-nsc to amdahl.  The practice of posting a preliminary set of rules for
-the next year was started this year.
+The [rules for 1997](rules.txt) suggested even more categories than in 1986.
+Hints for what to do and not to do were also given in the [rules](rules.txt).
+For example, a simple excessive abuse of /lib/cpp was discouraged unless the
+abuse was unusual.  The mailboxes for the contest were moved from nsc to amdahl.
+The practice of posting a preliminary set of rules for the next year was started
+this year.
 
-Rules and results were posted to comp.lang.c, comp.unix.wizards with
+[Rules](rules.txt) and results were posted to comp.lang.c and comp.unix.wizards with
 an announcement in news.announce.important.  Micro/Systems Journal
-published the 1987 winners.  Mark Horton included a version of the 1987
-winners in an appendix of his C book.  The first announcement of
-winners at the Summer 87 Usenix was helped by a small fly that
-danced all over the foils.
+published the 1987 winners.  [Mark R.
+Horton](https://www.amazon.com/stores/Mark-R.-Horton/author/B001HPGRB8) included a version of the [1987
+winners](../years.html#1987) in an appendix of his C book [Portable C Software International
+Edition](https://www.amazon.com/Portable-Software-Mark-R-Horton/dp/0138680507).
+The first announcement of winners at the Summer 87 Usenix was helped by a small
+fly that danced all over the foils.
 
 =-=