steamvr: Remove Monado 0.5 line with emulated index controllers

We didn't actually have that tag/relase.

steamvr.md

@@ -15,8 +15,7 @@ It does **not** make it possible to run OpenVR games and applications on Monado/
   * Distortion correction for OpenHMD, Panotools (PSVR), Vive/Vive Pro/Valve Index
   * Arbitrarily orientated displays from `get_view_pose()`, e.g. canted displays like Valve Index
 * All controllers supported by Monado
-  * Monado 0.5: All controllers emulate Valve Index controllers
-  * Monado v21.0.0: Monado supported controllers generate SteamVR input profiles.
+  * Since Monado v21.0.0: All controllers supported by Monado use generated SteamVR input profiles.
 
 # Registering the plugin