Updated Sidetree reference to v0.11.0

Merging v0.9.0 changes from `dev` to `master

v0.6.0 + fixed all high and critical vulnerabilities

Specified v0.5.0 protocol start time.

Just to clarify that this isn't always necessary

I like to keep install instructions minimal.

0.4.0

Issue decentralized-identity#28 - README - Using DPKI instead of PKI.