Format, typo, consistency check YYYY/README.md

There are many fixes made but a few questions remain so when I reach
those years I will address those then. Unfortunately, due to
infrastructure work right now, this is all I can say even though there
are a number of things I'd like to say.

1990/index.html

@@ -391,7 +391,7 @@
 on how to compile it 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 remarks for even more details.</p>
-<p>This year, the Grand Prize won a standing ovation at USENIX.</p>
+<p>This year, the <a href="theorem/index.html">Best of Show</a> won a standing ovation at USENIX.</p>
 <p>The <a href="stig/index.html">Strangest abuse of the rules</a> award was given this
 year to stress the fact that starting in <a href="../years.html#1991">1991</a>, entries
 should be shell-specific.</p>