Quick start guide clarity issues

[rmsamitha]

Description:

1. Better to have sub numbers of each of these sub topics for clarity i.e. “Generate APK configuration file for the API” , “Generate an access token to invoke APIs”
2. In section “Generate an access token to invoke APIs” https://apk.docs.wso2.com/en/latest/get-started/quick-start-guide/#generate-an-access-token-to-invoke-apis , mention where these client credentials are coming from. (i.e. inbuild oauth app ?)