Document how to handle CBOR objects concatenated in a stream

An EOF while decoding should not be used to signal the end of a stream.

If you're decoding a set of CBOR objects that are just concatenated together in a file without delimiters then do this:

```python
from cbor2 import CBORDecoder
with open('myfile.cbor', 'rb') as f:
decoder = CBORDecoder(f)
while f.peek(1): # Check that there's data at the next file position
print(decoder.decode())
print('Done!')
```

Otherwise wrap the items in an indefinite length array.

This is equivalent to how you would decode cbor from a network socket or queue, you always expect a complete item and if you don't it's corrupted data. Hence EOF errors do not make sense to pass up to the reader.