Remove reference to conjur.identity

This feature is missing per cyberark/conjur-api-go#53
so we shouldn't have it in the docs.

README.md

@@ -117,7 +117,6 @@ Specifically, it loads configuration from:
  * `.conjurrc` files, located in the home and current directories, or at the
     path specified by the `CONJURRC` environment variable.
  * Read `/etc/conjur.conf` as a `.conjurrc` file.
- * Read `/etc/conjur.identity` as a `netrc` file. Note that the user running must either be in the group `conjur` or root to read the identity file.
  * Environment variables:
    * Version
      * `CONJUR_MAJOR_VERSION` - must be set to `4` in order for summon-conjur to work with Conjur v4.9.