Update docs for conditions on events

[bnjjj]

          @bnjjj , is the difference that previously you could only use conditions on custom events? If so, we should also update this part of the documentation: https://www.apollographql.com/docs/router/configuration/telemetry/instrumentation/events/#condition

("Custom events can be configured to emit under specific conditions, " --> "Both custom and standard events ...")

Does the query batching limitation only apply to conditions on standard events, or custom ones too? Either way, would be good to call it out in that section too.

Originally posted by @Meschreiber in https://github.com/apollographql/router/pull/5556#discussion_r1657697952