Reading keys from environment variables

[Sandeep Singh]

Discussed in #248

^{Originally posted by omarkurt November 11, 2022}
Hello PD team,
I want to use environment variables instead of adding them in the configuration file as plaintext.

For example,

- provider: aws 
  id: staging
  aws_access_key: $ACCESS_KEY
  aws_secret_key: $SECRET_KEY

I did not see any information regarding using ENV variables.

---

Note:

Probably support to add in https://github.com/projectdiscovery/goflags so all other PD projects can utilize this enhancement.