Add docs on beta releases (GEA-13296) (#219)

Author: kenany

pangea-sdk/v3/README.md

@@ -101,6 +101,15 @@ fmt.Printf("Logged event: %s", pangea.Stringify(e))
 
 Full code for the above example available in [the examples directory](https://github.com/pangeacyber/pangea-go/blob/main/examples/audit/log_standard_schema.go).
 
+<a name="beta-releases"></a>
+
+## Beta releases
+
+Pre-release versions may be available with the `beta` denotation in the version
+number. These releases serve to preview beta services and APIs. Per Semantic
+Versioning, they are considered unstable and do not carry the same compatibility
+guarantees as stable releases.
+
 
 
    [Documentation]: https://pangea.cloud/docs/sdk/go/