Replace manual notes in documentation with admonitions

As they're generally prettier.

Requires https://github.com/element-hq/synapse/pull/19356

docs/usage/administration/admin_api/background_updates.md

@@ -49,9 +49,11 @@ This API allows pausing background updates.
 Background updates should *not* be paused for significant periods of time, as
 this can affect the performance of Synapse.
 
-*Note*: This won't persist over restarts.
+> [!NOTE]
+> This won't persist over restarts.
 
-*Note*: This won't cancel any update query that is currently running. This is
+> [!NOTE]
+> This won't cancel any update query that is currently running. This is
 usually fine since most queries are short lived, except for `CREATE INDEX`
 background updates which won't be cancelled once started.
 

docs/usage/administration/admin_api/federation.md

@@ -2,7 +2,8 @@
 
 This API allows a server administrator to manage Synapse's federation with other homeservers.
 
-Note: This API is new, experimental and "subject to change".
+> [!NOTE]
+> This API is new, experimental and "subject to change".
 
 ## List of destinations
 
@@ -62,9 +63,10 @@ The following query parameters are available:
 - `dir` - Direction of room order. Either `f` for forwards or `b` for backwards. Setting
   this value to `b` will reverse the above sort order. Defaults to `f`.
 
-*Caution:* The database only has an index on the column `destination`.
-This means that if a different sort order is used,
-this can cause a large load on the database, especially for large environments.
+> [!CAUTION]
+> The database only has an index on the column `destination`.
+> This means that if a different sort order is used,
+> this can cause a large load on the database, especially for large environments.
 
 **Response**
 

docs/usage/administration/admin_api/registration_tokens.md

@@ -1,6 +1,7 @@
 # Registration Tokens
 
-**Note:** This API is disabled when MSC3861 is enabled. [See #15582](https://github.com/matrix-org/synapse/pull/15582)
+> [!NOTE]
+> This API is disabled when MSC3861 is enabled. [See #15582](https://github.com/matrix-org/synapse/pull/15582)
 
 This API allows you to manage tokens which can be used to authenticate
 registration requests, as proposed in

docs/usage/administration/admin_faq.md

@@ -255,7 +255,8 @@ line to `/etc/default/matrix-synapse`:
 
     LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
 
-*Note*: You may need to set `PYTHONMALLOC=malloc` to ensure that `jemalloc` can accurately calculate memory usage. By default, Python uses its internal small-object allocator, which may interfere with jemalloc's ability to track memory consumption correctly. This could prevent the [cache_autotuning](../configuration/config_documentation.md#caches) feature from functioning as expected, as the Python allocator may not reach the memory threshold set by `max_cache_memory_usage`, thus not triggering the cache eviction process.
+> [!NOTE]
+> You may need to set `PYTHONMALLOC=malloc` to ensure that `jemalloc` can accurately calculate memory usage. By default, Python uses its internal small-object allocator, which may interfere with jemalloc's ability to track memory consumption correctly. This could prevent the [cache_autotuning](../configuration/config_documentation.md#caches) feature from functioning as expected, as the Python allocator may not reach the memory threshold set by `max_cache_memory_usage`, thus not triggering the cache eviction process.
 
 This made a significant difference on Python 2.7 - it's unclear how
 much of an improvement it provides on Python 3.x.

docs/usage/administration/monthly_active_users.md

@@ -20,8 +20,9 @@ So for example, if Synapse were to calculate the active users on the 15th July a
 A user is **never** considered active if they are either:
  - Part of the trial day cohort (described below)
  - Owned by an application service.
-   - Note: This **only** covers users that are part of an application service `namespaces.users` registration. The namespace
-     must also be marked as `exclusive`.
+   > [!NOTE]
+   > This **only** covers users that are part of an application service `namespaces.users` registration. The namespace
+   > must also be marked as `exclusive`.
 
 Otherwise, any request to Synapse will mark the user as active. Please note that registration will not mark a user as active *unless* 
 they register with a 3pid that is included in the config field `mau_limits_reserved_threepids`.

docs/usage/administration/useful_sql_for_admins.md

@@ -130,7 +130,8 @@ SELECT e.room_id, r.name, COUNT(e.event_id) cnt
 ```
 
 ## Show top 20 users on homeserver by sent events (messages) at last month:
-Caution. This query does not use any indexes, can be slow and create load on the database.
+> [!CAUTION]
+> This query does not use any indexes, can be slow and create load on the database.
 ```sql
 SELECT COUNT(*), sender
   FROM events

docs/usage/configuration/user_authentication/refresh_tokens.md

@@ -96,8 +96,9 @@ The following configuration options, in the `registration` section, are related:
   it more difficult for them to refresh in time, which may force them to need to
   re-authenticate using login credentials).
 
-**Note:** All four options above only apply when tokens are created (by logging in or refreshing).
-Changes to these settings do not apply retroactively.
+> [!NOTE]
+> All four options above only apply when tokens are created (by logging in or refreshing).
+> Changes to these settings do not apply retroactively.
 
 
 ### Using refresh token expiry to log out inactive sessions
@@ -113,9 +114,10 @@ account.
 `refreshable_access_token_lifetime` and this section assumes that to be the case
 for simplicity.)
 
-Note: this will only affect sessions using refresh tokens. You may wish to
-set a short `nonrefreshable_access_token_lifetime` to prevent this being bypassed
-by clients that do not support refresh tokens.
+> [!NOTE]
+> This will only affect sessions using refresh tokens. You may wish to
+> set a short `nonrefreshable_access_token_lifetime` to prevent this being bypassed
+> by clients that do not support refresh tokens.
 
 
 #### Choosing values that guarantee permitting some inactivity