Minor updates to several README.md files

Just some formatting fixes and in some cases add links to XQuartz for
macOS Mountain Lion and beyond. More entries (probably many more) have
to have that link added but those will be found and fixed in time.

1992/kivinen/README.md

@@ -7,11 +7,21 @@
 	Finland
 
 
-## Judges' comments:
+## To build:
+
 
 If your machine support the X Window System, Version 11:
 
-	make kivinen
+	make all
+
+NOTE: this entry requires `X11/Xlib.h` header file and the X11 library to
+compile. macOS users running Mountain Lion and later will need to download and
+install [XQuartz](https://www.xquartz.org) in order to compile and run this
+entry.
+
+
+## Judges' comments:
+
 
 The type of entertainment depends on number of arguments
 you have with the program.  :-)