Updated instructions on server/config.js

Added info when a couch admin/user already exists and is not created by the initcouch script.
Resolves #478

README.md

@@ -23,7 +23,7 @@ To install the frontend please do the following:
     2. Create admin user:
         1. If you have just installed CouchDB and have no admin user, please run `./script/initcouch.sh` in the folder you cloned the HospitalRun repo.  A user `hradmin` will be created with password: `test`.
         2. If you already have a CouchDB admin user, please run `./script/initcouch.sh USER PASS` in the folder you cloned the HospitalRun repo.  `USER` and `PASS` are the CouchDB admin user credentials.
-8. Copy the `server/config-example.js` to `server/config.js` in the folder you cloned the HospitalRun repo.
+8. Copy the `server/config-example.js` to `server/config.js` in the folder you cloned the HospitalRun repo.  If you already had a CouchDB admin user that you passed into the couch script (`./script/initcouch.sh USER PASS`), then you will need to modify the `couchAdminUser` and `couchAdminPassword` values in `server/config.js` to reflect those credentials.
 
 ### Experimental