Startup rename for extensions.json

[petrce]

Hi, would you mind to rename Startup to something more specific?
For more readable extensions.json in case of multiple extensions.
Thanks ;)

https://github.com/fbeltrao/AzureFunctionExtensions/blob/master/src/AzureFunctionExtensions/Startup.cs

[petrce]

eg like:
https://github.com/Azure/azure-functions-eventgrid-extension/blob/dev/src/EventGridExtension/EventGridWebJobsStartup.cs

[fbeltrao]

Hi @petrce,

Yes, it makes sense. You can always PR it 🙂