Add some missing configuration settings.

These settings are used in the deployed instance and mentioned elsewhere
in the README, but were missing from the base INI file and the
Configuration Guide section of the README.

config/base.ini

@@ -1,5 +1,8 @@
 [default]
 ASSETS_URL
+AZURE_ACCOUNT_NAME
+AZURE_STORAGE_KEY
+AZURE_TO_BUCKET_NAME
 BLOB_STORAGE_URL=http://localhost:8000/
 CAC_URL = http://localhost:8000/login-redirect
 CA_CHAIN = ssl/server-certs/ca-chain.pem
@@ -15,6 +18,11 @@ DISABLE_CRL_CHECK = false
 ENVIRONMENT = dev
 LIMIT_CONCURRENT_SESSIONS = false
 LOG_JSON = false
+MAIL_PASSWORD
+MAIL_PORT
+MAIL_SENDER
+MAIL_SERVER
+MAIL_TLS
 PERMANENT_SESSION_LIFETIME = 1800
 PGDATABASE = atat
 PGHOST = localhost