Add type caveat for contexts (#3557)

Co-authored-by: Katie Byers <[email protected]>

Author: imatwawana

src/platforms/common/enriching-events/context.mdx

@@ -36,7 +36,9 @@ Then, use <PlatformIdentifier name="set-context" /> and give the context a uniqu
 
 <PlatformContent includePath="enriching-events/set-context" />
 
-There are no restrictions for naming contexts or their fields. However, there is a set of conventions for common contexts. For more information, refer to the [contexts interface developer documentation](https://develop.sentry.dev/sdk/event-payloads/contexts/).
+There are no restrictions on context name. In the context object, all keys are allowed except for `type`, which is used internally. 
+
+Learn more about conventions for common contexts in the [contexts interface developer documentation](https://develop.sentry.dev/sdk/event-payloads/contexts/).
 
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