Add explanation of double colons to Collector config page (#4524)

Co-authored-by: Severin Neumann <[email protected]>

content/en/docs/collector/configuration.md

@@ -30,14 +30,22 @@ example:
 otelcol --config=customconfig.yaml
 ```
 
-You can also provide configurations using environment variables, YAML paths, or
-HTTP URIs. For example:
+You can also provide configurations using environment variables, HTTP URIs, or
+YAML paths. For example:
 
 ```shell
 otelcol --config=env:MY_CONFIG_IN_AN_ENVVAR --config=https://server/config.yaml
 otelcol --config="yaml:exporters::debug::verbosity: normal"
 ```
 
+{{% alert title="Tip" color="primary" %}}
+
+When referring to nested keys in YAML paths, make sure to use double colons (::)
+to avoid confusion with namespaces that contain dots. For example:
+`receivers::docker_stats::metrics::container.cpu.utilization::enabled: false`.
+
+{{% /alert %}}
+
 To validate a configuration file, use the `validate` command. For example:
 
 ```shell