FIGI — Add GH as an excluded prefix

Ghana uses GHG as a prefix for fixed income ISINs. Add "GH" to the exclusion list in the spec and in the code.

Add both GH and KY as excluded prefixes

This affects both the specification and the machine readable files.

Detailed:
Specification:
1. In section 6.1.2, add "GH" and "KY" to the list of excluded consonant combinations on page 20.
2. In section 8.2.4, add "GH" and "KY" to the list of excluded consonant combinations in both the regex expression and in the subsequent explanation of the regex expression.

machine readables:
in FinancialInstrumentIdentifier.rdf, change regex expression associated with Financial Instrument Global Identifiers to reflect the regex expression above.