Improve documentation of updating a dependency

BUILDING.md

@@ -78,17 +78,19 @@ For updated or newly added dependencies you need to add an entry to this verific
       </component>
 ```
 
+In case of updating a dependency, ensure to remove the unused entry of the outdated dependency manually from the verifcation.xml file.
+
 You can also automate the generation of this entry by running your build using the `--write-verification-metadata` commandline option:
 ```
 >./gradlew --write-verification-metadata sha256 precommit
 ```
 
-The `--write-verification-metadata` Gradle option is generally able to resolve reachable configurations, 
+The `--write-verification-metadata` Gradle option is generally able to resolve reachable configurations,
 but we use detached configurations for a certain set of plugins and tasks. Therefore, please ensure you run this option with a task that
 uses the changed dependencies. In most cases, `precommit` or `check` are good candidates.
 
-We prefer sha256 checksums as md5 and sha1 are not considered safe anymore these days. The generated entry 
-will have the `origin` attribute been set to `Generated by Gradle`. 
+We prefer sha256 checksums as md5 and sha1 are not considered safe anymore these days. The generated entry
+will have the `origin` attribute been set to `Generated by Gradle`.
 
 >A manual confirmation of the Gradle generated checksums is currently not mandatory.
 >If you want to add a level of verification you can manually confirm the checksum (e.g by looking it up on the website of the library)