Document usage of multiple collector config files

Signed-off-by: Swapnil Kulkarni <[email protected]>

content/en/docs/collector/configuration.md

@@ -39,6 +39,16 @@ otelcol --config=env:MY_CONFIG_IN_AN_ENVVAR --config=https://server/config.yaml
 otelcol --config="yaml:exporters::debug::verbosity: normal"
 ```
 
+You can also provide multiple configurations using multiple files at different
+paths. Each file can be a full/partial configuration and reference components
+from each other. For simplicity, if the merge of files does not constitute a
+complete configuration user will get an error since the defaults are not added
+by default. For example:
+
+```shell
+otelcol --cofig=file:/path/to/first/file --config=file:/path/to/second/file
+```
+
 {{% alert title="Tip" color="primary" %}}
 
 When referring to nested keys in YAML paths, make sure to use double colons (::)