Document readline() and readlines()

Author: dhalbert

shared-bindings/usb_cdc/Serial.c

@@ -45,7 +45,6 @@
 //|         descriptor and are included in the ``usb_cdc.serials`` tuple."""
 //|         ...
 //|
-
 //|     def read(self, size: int = 1) -> bytes:
 //|         """Read at most ``size`` bytes. If ``size`` exceeds the internal buffer size
 //|         only the bytes in the buffer will be read. If `timeout` is > 0 or ``None``,
@@ -64,6 +63,28 @@
 //|         :rtype: bytes"""
 //|         ...
 //|
+//|     def readline(self, size=-1) -> Optional[bytes]:
+//|         r"""Read a line, ending in a newline character ("\\n"), or
+//|         return everything readable if no newline is found and ``timeout`` is 0.
+//|         Return ``None`` in case of error.
+//|
+//|         This is a binary stream: the newline character cannot be changed.
+//|
+//|         :param int size: maximum number of characters to read. ``-1`` means as many as possible.
+//|         :return: the line read
+//|         :rtype: bytes or None"""
+//|         ...
+//|
+//|     def readlines(self) -> list:
+//|         """Read multiple lines as a list, using `readline()`
+//|
+//|         .. warning:: If ``timeout`` is ``None``,
+//|           `readlines()` will never return, because there is no way to indicate end of stream.
+//|
+//|         :return: a list of the line read
+//|         :rtype: list"""
+//|         ...
+//|
 //|     def write(self, buf: ReadableBuffer) -> int:
 //|         """Write as many bytes as possible from the buffer of bytes.
 //|