Add constant values of DTMF tone, and change the method name "setDTMF()" to "startTone()"
Update index.md
Update index.md
Update index.md
Update index.md
Adjust the constant variable names
Merge branch 'master' of github.com:masashiGMS/cordova-plugin-dtmf
Update the code
Fixed the DTMF volume
Merge pull request #2 from masashiGMS/master

Improve the code