Add documentation TransIP DNS TXT usage

root/defaults/dns-conf/transip.ini

@@ -1,6 +1,30 @@
 # Instructions: https://readthedocs.org/projects/certbot-dns-transip/
-# Convert the key to an RSA key (openssl rsa -in transip.key -out transip-rsa.key)
-# Place .key-file in the same directory as this file. Location "/config/dns-conf" is from within the container
+#
+# This DNS plugin can be used to generate SSL wildcard certificates via TransIP DNS TXT records
+#
+# Login with your TransIP account and go to My Account | API:
+# 1. API-settings: On
+#
+# 2. IP-address/ranges whitelist: Add a new authorized IP address (Swag Docker) to use the API
+#
+# 3. Generate a new Key Pair and copy the private key to a new transip.key file in the format:
+#    -----BEGIN PRIVATE KEY-----
+#    ...
+#    -----END PRIVATE KEY-----
+#
+# 4. Convert the key to an RSA key with command:
+#     openssl rsa -in transip.key -out /config/dns-conf/transip-rsa.key
+#
+# 5. Set permission
+#     chmod 600 /config/dns-conf/transip-rsa.key
+#
+# 6. Replace <transip_username> below with your TransIP username
+#
+# 7. Create wildcard certificate with Swag environment variables:
+#      SUBDOMAINS=wildcard
+#      VALIDATION=dns
+#      DNSPLUGIN=transip
 
 dns_transip_username = <transip_username>
-dns_transip_key_file = /config/dns-conf/transip-rsa.key
+dns_transip_key_file = /config/dns-conf/transip-rsa.key
+