README: Add release/distro/end-user recommendation

This may be useful for anyone trying a non-debug build and serve as
baseline for distros. Even for developers, when benchmarking kmod, it's
better to run a release-oriented kmod rather than the slow one due to
all debug/sanitizers.

By keeping the -D in the command line rather than in a ini file,
we also guarantee meson shows it in the summary, regardless of
mesonbuild/meson#13865.

Closes: #220
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: #221

README.md

@@ -52,6 +52,10 @@ Typical configuration and installation
     meson compile -C builddir/
     sudo meson install -C builddir/
 
+For end-user and distributions builds, it's recommended to use:
+
+    meson setup --buildtype release builddir/
+
 Alternatively you can try autotools build.
 NOTE: The autotools build is slated for removal with kmod v35