Adding documentation for Lock entity (#378)

* Adding documentation for Lock entity

* Cleanup from review

Remove unnecessary states section and unsupported usercode functions

docs/entity_lock.md

@@ -3,7 +3,7 @@ title: Lock Entity
 sidebar_label: Lock
 ---
 
-> This entry is incomplete. Contribution welcome.
+A lock entity is a device which is able to lock and unlock. Locking and unlocking can optionally be secured with a user code. Some locks also allow for opening of latches, this may also be secured with a user code.
 
 ## Properties
 
@@ -11,6 +11,54 @@ sidebar_label: Lock
 
 | Name | Type | Default | Description
 | ---- | ---- | ------- | -----------
+| changed_by | string | None | Describes what the last change was triggered by.
+| code_format | string | None | Regex for code format or None if no code is required.
+| is_locked | bool | None | Indication of whether the lock is currently locked. Used to determine `state`.
+
+### Supported Features
+
+Supported features constants are combined using the bitwise or (`|`) operator.
+
+| Constant | Description |
+|----------|--------------------------------------|
+| `SUPPORT_OPEN` | This lock supports opening the door latch.
 
 ## Methods
 
+### Lock
+
+```python
+class MyLock(LockDevice):
+
+    def lock(self, **kwargs):
+        """Lock all or specified locks. A code to lock the lock with may optionally be specified."""
+        
+    async def async_lock(self, **kwargs):
+        """Lock all or specified locks. A code to lock the lock with may optionally be specified."""
+```
+
+### Unlock
+
+```python
+class MyLock(LockDevice):
+
+    def unlock(self, **kwargs):
+        """Unlock all or specified locks. A code to unlock the lock with may optionally be specified."""
+        
+    async def async_unlock(self, **kwargs):
+        """Unlock all or specified locks. A code to unlock the lock with may optionally be specified."""
+```
+
+### Open
+
+Only implement this method if the flag `SUPPORT_OPEN` is set.
+
+```python
+class MyLock(LockDevice):
+
+    def open(self, **kwargs):
+        """Open (unlatch) all or specified locks. A code to open the lock with may optionally be specified."""
+        
+    async def async_open(self, **kwargs):
+        """Open (unlatch) all or specified locks. A code to open the lock with may optionally be specified."""
+```