Update known issues description

Author: Caitlin Bales (MSFT)

docs/known-issues.md

@@ -1,5 +1,5 @@
 # Known Issues
-Because of our close partnership with workload teams who surface API functionality through Graph, it is not always appropriate or feasible to introduce fixes to missing or broken functionality.
+The Graph library is a snapshot of the Microsoft Graph and may not be in sync with the current service. Because this library is generated, the generator may fail to address all potential scenarios in the Graph. Furthermore, service behavior changes may not be reflected in the library as the development of the library and the Microsoft Graph are loosely coupled.
 
 ## No Annotation Support
 [OData](http://docs.oasis-open.org/odata/odata/v4.0/errata03/os/complete/part3-csdl/odata-v4.0-errata03-os-part3-csdl-complete.html#_Toc453752630) allows workloads to specify additional information about their API surface including both functional and non-functional stipulations. We currently do not support these annotations in the [Generator](https://github.com/microsoftgraph/MSGraph-SDK-Code-Generator), due to hierarchical inheritance issues regarding said annotations. Therefore, there may be methods that do not produce valid queries to Graph. Please refer to the [Graph Docs](https://developer.microsoft.com/en-us/graph/docs/concepts/overview) as the source of truth in these discrepancies.