Update README to new GitHub markdown

README.md

@@ -43,7 +43,7 @@ class Data:
     value: Any
 ```
 
-> **Note**
+> [!NOTE]
 > It is not recommended to import the library this way, as it does not allow
 > you to introspect the annotations in other code. It is merely pointed out
 > for completeness.
@@ -110,12 +110,12 @@ As a reminder of semantic versioning, and a summary of the above:
 | **Minor**    |    X    |           | May add new features, can break type-checking     |
 | **Patch**    |    X    |     X     | Only intended for bugs                            |
 
-> **Warn**
+> [!WARNING]
 > Patch versions will be used to rectify any accidental breaking changes
 > or unintended bugs / behaviour, therefore you should **always** use
 > the latest patch version.
 
-> **Note**
+> [!NOTE]
 > Because patch versions may change previous behaviour, they *could* be
 > considered breaking, however the intention is always to fix unintended
 > behaviour or previous breaking changes which should not have been.