Catch up documentation with reality

• launch-client: Update release status

  As of 2022-08-25, the copy of scout in the GA Steam Client has a suitable version of s-r-launch-client, and the default branches of soldier, sniper, scout-on-soldier, Proton 7.0 and Proton experimental include the integration glue for s-r-launcher-interface-0. This lets us remove various warnings and caveats.

  Proton 6.0 and 5.13 will presumably never get this.

• launch-client: Say where to find it

• launch-client: We no longer need to pass --directory=''

  This is now the default in released versions, as part of the batch of quality-of-life changes in steamrt/tasks#145.

• launcher-interface-0: Move example to launch-client

  Let's keep all the examples together.

• compat-tool-interface: Non-Steam launch options can have %command% now

  The feature request https://github.com/ValveSoftware/steam-for-linux/issues/6046 was implemented in March 2022 releases of Steam.