Update README.md

README.md

+# Serial framing protocol
+
+This library provides a way to frame data safely (including a corruption check).
+
+## How-to-use
+
+### Framing data
+
+```python
+# The data to be framed
+data = bytearray([0x12, 0x34, 0x56])
+
+# Frame and store the result in framed_data
+framed_data = bytearray()
+frame_data(data, framed_data)
+
+# Print the hexadecimal representation of the result
+# This will return b'7e0003123456bf127f'
+print(binascii.hexlify(framed_data))
+```
+
+The actual byte sent are `0x7e 0x0 0x3 0x12 0x34 0x56 0xbf 0x12 0x7f`.
+In those bytes:
+- `0x7e` is the start of frame flag (1 byte)
+- `0x0 0x3` is the data size (2 bytes)
+- `0x12 0x34` is the data we are sending (n bytes)
+- `0xbf 0x12` is the cyclic redundancy check (2 bytes), it helps checking for any corruption of the data
+- `0x7f` is the end of frame flag (1 byte)
+
+### Unframing data
+
+```python
+# The frame to unframe the data from
+framed_data = bytearray([0x7e, 0x0, 0x3, 0x12, 0x34, 0x56, 0xbf, 0x12, 0x7f])
+
+# Unframe and store the result in unframed_data
+unframed_data = bytearray()
+unframe_data(framed_data, unframed_data)
+
+# Print the hexadecimal representation of the result
+# This will return b'123456'
+print(binascii.hexlify(unframed_data))
+```