Add did:ling method

[sujiny-tech]

DID Method Registration

As a DID method registrant, I have ensured that my DID method registration complies with the following statements:

• [x] The DID Method specification defines the DID Method Syntax.
• [x] The DID Method specification defines the Create, Read, Update, and Deactivate DID Method Operations.
• [x] The DID Method specification contains a Security Considerations section.
• [x] The DID Method specification contains a Privacy Considerations section.
• [x] The JSON file I am submitting has passed all automated validation tests below.
• [x] The JSON file contains a contactEmail address [OPTIONAL].
• [x] The JSON file contains a verifiableDataRegistry entry [OPTIONAL].