Updated docs description for pilot/testflight action

[RishabhTayal]

Thanks for contributing to fastlane! Before you submit your pull request, please make sure to check the following boxes:

• Run bundle exec rspec from the root directory.
• Run bundle exec rubocop -a to ensure the code style is valid
• Read the Contribution Guidelines
• We currently don't accept new actions, please publish a plugin instead, more information in Plugins.md

Before submitting a pull request, we appreciate if you create an issue first to discuss the change 👍

[KrauseFx]

Nice change, thanks for all your contribution 👍

[RishabhTayal]

Clarifies this tweet in docs.