Share examples of other projects using 'build'

README.md

@@ -30,6 +30,16 @@ for at least one much larger program.
   only built the first time, unless you request a "deep" build)
 * Portable (tested on Linux, macOS and Windows platforms)
 
+You can find examples of how I use 'build' in some of my other projects:
+
+* Flight recorder:
+  https://github.com/c3d/recorder/blob/master/Makefile
+* XL programming language:
+  https://github.com/c3d/XL-programming-language/blob/master/xlr/Makefile
+* ELFE programming language:
+  https://github.com/c3d/elfe/blob/master/src/Makefile
+* XL reboot:
+  https://github.com/c3d/xl/blob/master/Makefile
 
 ## Using build