docs: Use spec_version (#758)

Signed-off-by: Arthur Pitman <[email protected]>

documentation/dynatrace-conf-yaml-file.md

@@ -9,12 +9,17 @@ The configuration file must be a well-formed [YAML file](https://yaml.org/). The
 
 | Key name| Description |
 |---|---|
-| `specVersion` |Specification version |
+| `spec_version` |Specification version |
 | `dtCreds` | Dynatrace API credentials secret name|
 | `dashboard` | Dashboard SLI-mode configuration|
 | `attachRules` | Attach rules for connecting Dynatrace entities with events |
 
 
+## Specification version (`spec_version`)
+
+Currently, `spec_version` is set to `0.1.0`.
+
+
 ## Dynatrace API credentials secret name (`dtCreds`)
 
 The `dtCreds` property allows you to specify the  name of the Kubernetes secret containing Dynatrace API credentials. By default, the value `dynatrace` is used.  Further details about the structure of this secret and how to create it can be found the section [Create a Dynatrace API credentials secret](project-setup.md#1-create-a-dynatrace-api-credentials-secret).