Add errors factory skeleton

client/doc/modules/types.rst

@@ -3,4 +3,67 @@ Types
 
 .. automodule:: telethon.types
 
+Errors
+------
+
 .. autoclass:: telethon.RpcError
+
+.. currentmodule:: telethon
+
+.. data:: errors
+
+    Factory-object returning subclasses of :class:`RpcError`.
+
+    You can think of it as a module with an infinite amount of error types in it.
+
+    When accessing any attribute in this object, a subclass of :class:`RpcError` will be returned.
+
+    The returned type will catch :class:`RpcError` if the :attr:`RpcError.name` matches the attribute converted to ``SCREAMING_CASE``.
+
+    For example:
+
+    .. code-block:: python
+
+        from telethon import errors
+
+        try:
+            await client.send_message(chat, text)
+        except errors.FloodWait as e:
+            await asyncio.sleep(e.value)
+
+    The code above is equivalent to the following:
+
+    .. code-block:: python
+
+        from telethon import RpcError
+
+        try:
+            await client.send_message(chat, text)
+        except RpcError as e:
+            if e.name == 'FLOOD_WAIT':
+                await asyncio.sleep(e.value)
+            else:
+                raise
+
+    This factory object is merely a convenience.
+
+    There is one exception, and that is when the attribute name starts with ``'Code'`` and ends with a number:
+
+    .. code-block:: python
+
+        try:
+            await client.send_message(chat, text)
+        except errors.Code420:
+            await asyncio.sleep(e.value)
+
+    The above snippet is equivalent to checking :attr:`RpcError.code` instead:
+
+    .. code-block:: python
+
+        try:
+            await client.send_message(chat, text)
+        except RpcError as e:
+            if e.code == 420:
+                await asyncio.sleep(e.value)
+            else:
+                raise