Fix kramdown warnings in docs

doc/administration/monitoring/prometheus/index.md

@@ -301,7 +301,7 @@ Prometheus has several custom flags to configure local storage:
 
 - `storage.tsdb.retention.time`: when to remove old data. Defaults to `15d`. Overrides
   `storage.tsdb.retention` if this flag is set to anything other than the default.
-- `storage.tsdb.retention.size`: [EXPERIMENTAL] the maximum number of bytes of storage blocks to
+- `storage.tsdb.retention.size`: (experimental) the maximum number of bytes of storage blocks to
   retain. The oldest data is removed first. Defaults to `0` (disabled). This flag is experimental
   and may change in future releases. Units supported: `B`, `KB`, `MB`, `GB`, `TB`, `PB`, `EB`. For
   example, `512MB`.

doc/user/project/merge_requests/code_quality.md

@@ -592,10 +592,10 @@ plugins:
 If your merge requests do not show any code quality changes when using a custom tool,
 ensure that the line property is an `integer`.
 
-### Code Quality CI job with Code Climate plugins enabled fails with error "engine <plugin_name> ran for 900 seconds and was killed"
+### Code Quality CI job with Code Climate plugins enabled fails with error
 
-If you enabled any of the Code Climate plugins, and the Code Quality CI job fails with the error below,
-it's likely the job takes longer than the default timeout of 900 seconds.
+If you enabled any of the Code Climate plugins, and the Code Quality CI job fails with the error
+below, it's likely the job takes longer than the default timeout of 900 seconds:
 
 ```shell
 error: (CC::CLI::Analyze::EngineFailure) engine pmd ran for 900 seconds and was killed