meson: add note about version in pkg-config file

See also benhoyt#123.

Signed-off-by: Stephan Lachnit <[email protected]>

README.md

@@ -139,6 +139,7 @@ Some differences between inih and Python's [ConfigParser](http://docs.python.org
 * All compile-time options are implemented in Meson as well, you can take a look at [meson_options.txt](https://github.com/benhoyt/inih/blob/master/meson_options.txt) for their definition. These won't work if `distro_install` is set to `true`.
 * If you want to use inih for programs which may be shipped in a distro, consider linking against the shared libraries. The pkg-config entries are `inih` and `INIReader`.
 * In case you use inih as a Meson subproject, you can use the `inih_dep` and `INIReader_dep` dependency variables. You might want to set `default_library=static` and `distro_install=false` for the subproject. An official Wrap is provided on [WrapDB](https://wrapdb.mesonbuild.com/inih).
+* For packagers: if you want to tag the version in the pkg-config file, you will need to do this downstream. Add `version : '<version_as_int>',` after the `license` tag in the `project()` function and `version : meson.project_version(),` after the `soversion` tag in both `library()` functions.
 
 ## Building from vcpkg ##