added some info on this demo package

install/demo/fpcdemos.txt

@@ -0,0 +1,16 @@
+FPC demo package
+================
+This packages contains the following subdirs:
+
+- text   texmode demos (should run everywhere)
+- graph  demos that use the graph unit (runs nearly everywhere)
+         includes gameunit (text&graph), outputs to another subdir level
+- modex  demos that make extensive use of modeX (runs with go32v2 only)
+- win32  demos that are win32 specific
+
+To build the programs simply type 'make' in the base dir.
+
+If you want to add further sampels, edit Makefile.fpc
+and rebuild the real Makefile by entering 'fpcmake'.
+This is a special fpc generic utility to simplify
+platform independent makfile generation to the user.