add missing polly apis (dotnet#5222)

Author: gewarren

_zip/missingapi.yml

@@ -31,10 +31,34 @@ references:
 - uid: Microsoft.Extensions.Localization.Internal.IResourceStringProvider
   name: IResourceStringProvider
   fullname: Microsoft.Extensions.Localization.Internal.IResourceStringProvider
+- uid: Polly.Context
+  name: Context
+  fullname: Polly.Context
+  href: https://github.com/App-vNext/Polly/wiki/Keys-and-Context-Data
+- uid: Polly.IAsyncPolicy
+  name: IAsyncPolicy
+  fullname: Polly.IAsyncPolicy
+  href: https://github.com/App-vNext/Polly/wiki
+- uid: Polly.IAsyncPolicy`1
+  name: IAsyncPolicy`1
+  fullname: Polly.IAsyncPolicy`1
+  href: https://github.com/App-vNext/Polly/wiki
+- uid: Polly.Policy
+  name: Policy
+  fullname: Polly.Policy
+  href: https://github.com/App-vNext/Polly/wiki
+- uid: Polly.Policy.TimeoutAsync``1(System.Int32)
+  name: TimeoutAsync``1(System.Int32)
+  fullname: Polly.Policy.TimeoutAsync``1(System.Int32)
+  href: https://github.com/App-vNext/Polly/wiki
+- uid: Polly.PolicyBuilder`1
+  name: PolicyBuilder`1
+  fullname: Polly.PolicyBuilder`1
+  href: https://github.com/App-vNext/Polly/wiki
 - uid: Polly.Registry.PolicyRegistry
   name: PolicyRegistry
   fullname: Polly.Registry.PolicyRegistry
-  href: https://github.com/App-vNext/Polly/wiki
+  href: https://github.com/App-vNext/Polly/wiki/PolicyRegistry
 - uid: Polly.Registry.IPolicyRegistry`1
   name: IPolicyRegistry<TKey>
   fullname: Polly.Registry.IPolicyRegistry<TKey>