fix many internal links

Fixed a number of internal links that need to
go to the GitHub site.

Ran `make www` to perform the above.

1989/README.md

@@ -8,15 +8,15 @@ You may then wish to look at the Author's remarks for even more details.
 Instructions for use: Run `make` to compile entries (it is possible that on
 System V or non-Unix systems the Makefile needs to be changed).
 
-The Makefile for ["Best self modifying program"](fubar/indx.html) always uses
+The Makefile for ["Best self modifying program"](fubar/index.html) always uses
 the most portable version because there is no loss of functionality in
-using it.  In the case of the ["Best game"](tromp/README) entry, however, some
+using it.  In the case of the ["Best game"](tromp/index.html) entry, however, some
 functionality is lost in the portable version and so its Makefile uses
 the original program.
 
 This year, the [Best of Show](jar.2/index.html) was given to the most useful program.
 
-The ["Strangest abuse of the rules"](jar.1/indx.html) award was given this year
+The ["Strangest abuse of the rules"](jar.1/index.html) award was given this year
 to stress the fact that starting in 1990, compiling entries must result a
 regular executable file.