add documentation for #fetch_rate and #fix_response_json_data
add documentation for #fetch_rate and #fix_response_json_data

bonusly/google_currency,bonusly/google_currency,basex/google_currency,Hates/google_currency,Hates/google_currency,sagmor/google_currency,basex/google_currency,RubyMoney/google_currency,hothero/google_currency,RubyMoney/google_currency