Update docs for new API

[jsouter]

running pyright on docs reveals some issues with TemperatureControllerHandler

/workspaces/FastCS/docs/snippets/dynamic.py
  /workspaces/FastCS/docs/snippets/dynamic.py:66:31 - error: Cannot access attribute "controller" for class "TemperatureControllerHandler*"
    Attribute "controller" is unknown (reportAttributeAccessIssue)
  /workspaces/FastCS/docs/snippets/dynamic.py:74:20 - error: Cannot access attribute "controller" for class "TemperatureControllerHandler*"
    Attribute "controller" is unknown (reportAttributeAccessIssue)
  /workspaces/FastCS/docs/snippets/dynamic.py:85:15 - error: Method "initialise" overrides class "BaseController" in an incompatible manner
    Positional parameter count mismatch; base method has 1, but override has 2 (reportIncompatibleMethodOverride)
3 errors, 0 warnings, 0 informations 

Probably just need to add an initialise and fix the _controller/self.controller discrepancy.

[GDYendell]

Re-test this once we have replaced Handlers with AttributeIO