Update meson.build

Moved example dir variable into source meson.build script, fixed comment.

examples/example_4/meson.build

 ###################################################################################
 #                                                                                 #
-# NAME: examples/example_4/meson.build                                            #
+# NAME: meson.build                                                               #
 #                                                                                 #
 # AUTHOR: Mike Karlesky, Mark VanderVoord, Greg Williams.                         #
 # WRITTEN BY: Michael Brockus.                                                    #
@@ -9,12 +9,9 @@
 #                                                                                 #
 ###################################################################################
 
-
 project('example-4', 'c')
 
 unity_dep = dependency('unity', fallback : ['unity', 'unity_dep'])
 
-example_dir = include_directories('.', join_paths('.', 'src'))
-
 subdir('src')
-subdir('test')
+subdir('test')
\ No newline at end of file