Update help for telemetry level filters

Author: NickLarsenNZ

modules/concepts/pages/observability/telemetry.adoc

@@ -47,7 +47,7 @@ telemetry:
 ----
 
 <1> Boolean: `true`, `false`
-<2> Enum: `error`, `warn`, `info`, `debug`, trace`
+<2> String: `error`, `warn`, `info`, `debug`, `trace`, `off` (and https://rustc-dev-guide.rust-lang.org/tracing.html#query-level-filters[more complex filters])
 <3> Enum: `plain`, `json`
 
 == File logs
@@ -66,7 +66,7 @@ telemetry:
 ----
 
 <1> Boolean: `true`, `false`
-<2> Enum: `error`, `warn`, `info`, `debug`, `trace`
+<2> String: `error`, `warn`, `info`, `debug`, `trace`, `off` (and https://rustc-dev-guide.rust-lang.org/tracing.html#query-level-filters[more complex filters])
 <3> Enum: `never`, `daily`, `hourly`, `minutely`
 <4> Unsigned Integer
 
@@ -89,5 +89,5 @@ telemetry:
 ----
 
 <1> Boolean: `true`, `false`
-<2> Enum: `error`, `warn`, `info`, `debug`, `trace`
+<2> String: `error`, `warn`, `info`, `debug`, `trace`, `off` (and https://rustc-dev-guide.rust-lang.org/tracing.html#query-level-filters[more complex filters])
 <3> String: E.g. `https://my-collector:4317` (Note: it must contain the scheme)