Document being-activated

include/clap/plugin.h

@@ -61,6 +61,7 @@ typedef struct clap_plugin {
    // In this call the plugin may allocate memory and prepare everything needed for the process
    // call. The process's sample rate will be constant and process's frame count will included in
    // the [min, max] range, which is bounded by [1, INT32_MAX].
+   // In this call the plugin may call host-provided methods marked [being-activated].
    // Once activated the latency and port configuration must remain constant, until deactivation.
    // Returns true on success.
    // [main-thread & !active]