Minor Fixes

[wilwade]

While writing the documentation, there are some minor fixes. Here's the tracking list of them

• [x] Should be be start-gateway.sh or just start.sh
• [x] We should remove the default Provider Id from the setup script
• [x] Update "DEFAULT seed phrase needed" -> "Required for Testnet"
• [x] Remove script option for "Enter the location of the Content DB"
• [ ] :rocket: You can access the Gateway at http://localhost:3000/ :rocket: Shouldn't this be Social App Template?
• [ ] Social App Template Backend Swagger Docs title is wrong: "DSNP Gateway Prototype API Documentation"