fix: Add more context data to flagpole documentation (#13394)

Author: markstory

develop-docs/backend/application-domains/feature-flags/flagpole.mdx

@@ -148,6 +148,10 @@ Here are some common properties we surface via our Sentry and GetSentry context
 
 : The project's slug
 
+`project_platform` [str]
+
+: The project's platform
+
 **User Context Properties (If checking a flag with an actor)**
 
 `user_id` [int]
@@ -158,6 +162,18 @@ Here are some common properties we surface via our Sentry and GetSentry context
 
 : The active user's email address. This should only contain Sentry employee email addresses.
 
+`user_domain` [str]
+
+: The domain of the active user's email address.
+
+`user_is-staff` [bool]
+
+: Is set to `true` for users that have `is_staff`.
+
+`user_is-superuser` [bool]
+
+: Is set to `true` for users that have `is_superuser`.
+
 
 To see the latest context properties available, check out the repo-specific context builders: