add dns_opusdns provider information

dnsapi2.md

@@ -116,6 +116,7 @@
 - [192. Use Sotoon domain API](#dns_sotoon)
 - [193. Use mgw-media.de DNS API](#dns_mgwm)
 - [194. Use VirakCloud DNS API](#dns_virakcloud)
+- [195. Use OPusDNS DNS API](#dns_opusdns)
 - [Use custom API](#dns_myapi)
 - [Use lexicon DNS API](#dns_lexicon)
 
@@ -2962,8 +2963,29 @@ Report any bugs or issues [here](https://github.com/acmesh-official/acme.sh/issu
 Report any bugs or issues [here](https://github.com/acmesh-official/acme.sh/issues/6737)
 
 
+<a name="dns_opusdns"> 
+
+## 195. Use OpusDNS DNS API
+
+1.  Get your API Token from your OpusDNS account here: https://app.opusdns.com/
+
+2.  Export the token as an environment variable:
+
+    ```sh
+    export OPUSDNS_API_Key="opk_..."
+    ```
+
+3.  Issue the certificate:
+
+    ```sh
+    ./acme.sh --issue --dns dns_opusdns -d example.com -d www.example.com
+    ```
+
+Report any bugs or issues [here](https://github.com/acmesh-official/acme.sh/issues/6761)
+
 <a name="dns_myapi"/>
 
+
 ## Use custom API
 
 If your API is not supported yet, you can write your own DNS API.