document additional available methods

[sekur]

There are additional methods available that should be described in the README.

Below are comprehensive listing of public methods (undocumented ones marked with *).

module-level:

• yang.parse
• yang.compose
• yang.require
• yang.register
• yang.use*
• yang.resolve*

Yang/Expression/Element instance:

• bind
• eval
• extends
• toString
• toObject
• locate*
• match*
• access*
• resolve*
• clone*
• merge*
• update*
• lookup*
• error*
• debug*