Add --dev option to suggested install cmd (#1289)
Add --dev option to suggested install cmd (#1289)

Prettier should be saved to `devDependencies`
existentialism/prettier,arijs/prettier-miscellaneous,arijs/prettier-with-tabs,prettier/prettier,existentialism/prettier,azz/prettier,rattrayalex/prettier,azz/prettier,Skywalker13/prettier-space-parenthesis,jlongster/prettier,yamafaktory/prettier,arijs/prettier-miscellaneous,despairblue/prettier,rattrayalex/prettier,prettier/prettier,azz/prettier,prettier/prettier,despairblue/prettier,Skywalker13/prettier-space-parenthesis,azz/prettier,lydell/prettier,Skywalker13/prettier-space-parenthesis,Skywalker13/prettier-space-parenthesis,yamafaktory/prettier,prettier/prettier,lydell/prettier,lydell/prettier,rattrayalex/prettier,arijs/prettier-with-tabs,arijs/prettier-miscellaneous,existentialism/prettier,arijs/prettier-miscellaneous,existentialism/prettier,lydell/prettier