add upgrade and compatibility notes to README for country select for #1060
add country_select 2.x syntax to CountryInput docs for #1060
point country_select docs to the right reference gem for #1080
add compatibility and upgrade notes for country_select 2.x for #1060
fix typo
Merge pull request #1061 from justinfrench/note-country-select-compatibility-issues

Note country_select compatibility issues