Updated How to use OVH domain api (markdown)

How-to-use-OVH-domain-api.md

@@ -1 +1,53 @@
-TODO:
+### 1. Create application key and secret
+https://eu.api.ovh.com/createApp/
+
+## 2. Set api key and api secret.
+
+```
+# application key
+export OVH_AK="your application key"
+
+# application secret
+export OVH_AS="your application secret"
+
+acme.sh --issue -d   mydomain.com   --dns   dns_ovh
+```
+
+If you are first time using OVH api,  you are required to authenticate the api. (This only happens the first time.)
+
+You will see some thing like bellow:
+
+```
+[Thu, Aug 25, 2016 10:54:03] Using OVH endpoint: ovh-eu
+[Thu, Aug 25, 2016 10:54:04] OVH consumer key is empty, Let's get one:
+[Thu, Aug 25, 2016 10:54:05] Please open this link to do authentication: https://eu.api.ovh.com/auth/?credentialToken=n0Qbjm6wBdBr2KiSqIuYSEnixxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+[Thu, Aug 25, 2016 10:54:05] Here is a guide for you: https://github.com/Neilpang/acme.sh/wiki/How-to-use-OVH-domain-api
+[Thu, Aug 25, 2016 10:54:05] Please retry after the authentication is done.
+[Thu, Aug 25, 2016 10:54:05] Error add txt for domain:_acme-challenge.mytest.mydomain.com
+
+```
+
+
+## 3. Authentication the api key.
+ (This only happens the first time.)
+
+Open the link above:
+```
+https://eu.api.ovh.com/auth/?credentialToken=n0Qbjm6wBdBr2KiSqIuYSEnixxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+```
+
+In the page, please  select "Unlimited" for the Validity.
+
+Click "Authorize Access"
+
+
+## 4. Then go back to try again.
+
+```
+acme.sh --issue -d   mydomain.com   --dns   dns_ovh
+```
+
+Done.
+
+
+