doc: updated the nginx compatibility list.

Author: agentzh

README.markdown

@@ -1606,6 +1606,11 @@ Compatibility
 
 The following versions of Nginx should work with this module:
 
+* **1.16.x**
+* **1.15.x**                      (last tested: 1.15.8)
+* **1.14.x**
+* **1.13.x**                      (last tested: 1.13.6)
+* **1.12.x**
 * **1.11.x**                      (last tested: 1.11.2)
 * **1.10.x**
 * **1.9.x**                       (last tested: 1.9.15)