[typo] LDP Context IRI

[tkanai]

The LDP Context IRI written in 4.1 Container Retrieval (Protocol) must be
http://www.w3.org/ns/ldp.jsonld

("c" following "w3" should be removed.)

[iherman]

Summary: In the section after the bullet items at the beginning of 4.1 the IRI in the text must be changed.