meson: install headers and pkg-config file

meson.build

@@ -17,6 +17,16 @@ magic_enum_dep = declare_dependency(
     compile_args: magic_enum_args,
 )
 
+# install header and pkg-config file
+install_subdir('include/magic_enum', install_dir: get_option('includedir'))
+pkg = import('pkgconfig')
+pkg.generate(
+  name: 'magic_enum',
+  description: 'A library that provides static reflection for enums, work with any enum type without any macro or boilerplate code.',
+  url: 'https://github.com/Neargye/magic_enum',
+  extra_cflags: magic_enum_args,
+)
+
 if get_option('test')
     subdir('test')
 endif