Mention callbacks introduced in v1.37.0

According to the documentation introduced in #10062

Author: babolivier

docs/modules/spam_checker_callbacks.md

@@ -10,6 +10,8 @@ The available spam checker callbacks are:
 
 ### `check_event_for_spam`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def check_event_for_spam(event: "synapse.events.EventBase") -> Union[bool, str]
 ```
@@ -46,6 +48,8 @@ any of the subsequent implementations of this callback.
 
 ### `user_may_invite`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def user_may_invite(inviter: str, invitee: str, room_id: str) -> bool
 ```
@@ -101,6 +105,8 @@ any of the subsequent implementations of this callback.
 
 ### `user_may_create_room`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def user_may_create_room(user: str) -> bool
 ```
@@ -149,6 +155,8 @@ any of the subsequent implementations of this callback.
 
 ### `user_may_create_room_alias`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def user_may_create_room_alias(user: str, room_alias: "synapse.types.RoomAlias") -> bool
 ```
@@ -164,6 +172,8 @@ any of the subsequent implementations of this callback.
 
 ### `user_may_publish_room`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def user_may_publish_room(user: str, room_id: str) -> bool
 ```
@@ -179,6 +189,8 @@ any of the subsequent implementations of this callback.
 
 ### `check_username_for_spam`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def check_username_for_spam(user_profile: Dict[str, str]) -> bool
 ```
@@ -201,6 +213,8 @@ any of the subsequent implementations of this callback.
 
 ### `check_registration_for_spam`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def check_registration_for_spam(
     email_threepid: Optional[dict],
@@ -232,6 +246,8 @@ this callback.
 
 ### `check_media_file_for_spam`
 
+_First introduced in Synapse v1.37.0_
+
 ```python
 async def check_media_file_for_spam(
     file_wrapper: "synapse.rest.media.v1.media_storage.ReadableFileWrapper",