add documentation

README.md

@@ -335,6 +335,7 @@ You don't have to do anything manually!
 1. DNSimple API
 1. NS1.com API
 1. DuckDNS.org API
+1. Yandex PDD API (https://pdd.yandex.ru)
 1. Name.com API
 1. Dyn Managed DNS API
 

dnsapi/README.md

@@ -522,6 +522,21 @@ account file will always store the lastly used domain name.
 
 For issues, please report to https://github.com/raidenii/acme.sh/issues.
 
+
+## 27. Use pdd.yandex.ru API
+
+```
+export PDD_Token="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
+```
+
+Follow these instructions to get the token for your domain https://tech.yandex.com/domain/doc/concepts/access-docpage/
+```
+acme.sh --issue --dns dns_yandex -d mydomain.example.org
+```
+
+For issues, please report to https://github.com/non7top/acme.sh/issues.
+
+
 ## 28. Use Name.com API
 
 You'll need to fill out the form at https://www.name.com/reseller/apply to apply