Fix backend-telemetry.md format (#5107)

* Update backend-telemetry.md

Fix doc format.

* Update backend-setup.md

Remove out-of-date inventory documentation.

docs/en/setup/backend/backend-setup.md

@@ -128,8 +128,8 @@ If you want to override it, please follow Java and OS documents to do so.
 SkyWalking provides browser UI, CLI and GraphQL ways to support extensions. But some users may have the idea to query data 
 directly from the storage. Such as in ElasticSearch case, Kibana is a great tool to do this.
 
-In default, due to reduce memory, network and storage space usages, SkyWalking saves id(s) only in the entity and metadata saved in the
-`*_inventory` entities only. But these tools usually don't support nested query, or don't work conveniently. In this special case,
+In default, due to reduce memory, network and storage space usages, SkyWalking saves based64-encoded id(s) only in the metrics entities. 
+But these tools usually don't support nested query, or don't work conveniently. In this special case,
 SkyWalking provide a config to add all necessary name column(s) into the final metrics entities with ID as a trade-off.
 
 Take a look at `core/default/activeExtraModelColumns` config in the `application.yaml`, and set it as `true` to open this feature.

docs/en/setup/backend/backend-telemetry.md

@@ -50,7 +50,7 @@ telemetry:
   prometheus:
     host: 127.0.0.1
     port: 1543
-```.
+```
 
 2. Setting up prometheus fetcher