Add dev blog about deprecating hass.helpers (#2130)

* Change add_devices to add_entities

* Add dev blog about deprecating `hass.helpers`

* Title

* Update versions

blog/2024-03-30-deprecate-hass-helpers.md

@@ -0,0 +1,37 @@
+---
+author: Jan-Philipp Benecke
+authorURL: https://github.com/jpbede
+authorImageURL: https://avatars.githubusercontent.com/u/3989428?s=96&v=4
+title: "Deprecate hass.helpers usage"
+---
+
+As of Home Assistant 2024.5, we deprecate the use of `hass.helpers`.
+Using `hass.helpers` will issue a warning in the logs.
+Authors of custom integrations are encouraged to update their code 
+to prevent any issues before Home Assistant 2024.11.
+
+Starting from Home Assistant 2024.11, `hass.helpers` will be removed and will no longer work.
+
+Integrations that use `hass.helpers` should be updated to import the functions and classes directly
+from the integration package and pass the `hass` object as first parameter.
+
+### New example
+
+```python
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers.aiohttp_client import async_get_clientsession
+
+async def async_setup(hass: HomeAssistant, config):
+    """Set up the component."""
+    client = async_get_clientsession(hass)
+```
+
+### Old example
+
+```python
+from homeassistant.core import HomeAssistant
+
+async def async_setup(hass: HomeAssistant, config):
+    """Set up the component."""
+    client = hass.helpers.aiohttp_client.async_get_clientsession()
+```