message: Remove GITHUB_USERNAME from the readme
  * Remove GITHUB_USERNAME from the readme
  It's no longer used.
  * Improve wording
  * minor wording improvements
diff: @@ -187,12 +187,11 @@ cargo run -- build crate --local /path/to/source
  # Adds a directory into database to serve with `staticfile` crate.
  cargo run -- database add-directory <DIRECTORY> [PREFIX]
  -# Updates github stats for crates.
  -# You need to set CRATESFYI_GITHUB_USERNAME, CRATESFYI_GITHUB_ACCESSTOKEN
  -# environment variables in order to run this command.
  -# Set DOCSRS_GITLAB_ACCESSTOKEN to raise the rate limit,
  +# Updates repository stats for crates.
  +# You need to set the CRATESFYI_GITHUB_ACCESSTOKEN
  +# environment variable in order to run this command.
  +# Set DOCSRS_GITLAB_ACCESSTOKEN to raise the rate limit for GitLab repositories,
  # or leave it blank to fetch repositories at a slower rate.
  -# You can set this environment variables in the .env file.
  cargo run -- database update-repository-fields
  ```
  