Add 3.9 cipher lists to the docs

Author: stoty

zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md

@@ -1879,6 +1879,17 @@ and [SASL authentication for ZooKeeper](https://cwiki.apache.org/confluence/disp
 
     Default: **true** (3.9.0+), **false** (3.8.x)
 
+##### Cipher handling changes
+
+From 3.5.5 to 3.9 a hard coded default cipher list was used, with the ordering
+dependent on whether it is run Java 8 or a later version.
+
+In 3.9 the list on Java 8 is: *TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,     TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384     TLS_AES_256_GCM_SHA384,TLS_AES_128_GCM_SHA256, TLS_CHACHA20_POLY1305_SHA256*
+
+In 3.10 the list on Java 8 is: *TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384     TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,     TLS_AES_256_GCM_SHA384,TLS_AES_128_GCM_SHA256, TLS_CHACHA20_POLY1305_SHA256*
+
+In 3.10 there is no hardcoded list, and the JVM defaults are used.
+
 <a name="Experimental+Options%2FFeatures"></a>
 
 #### Experimental Options/Features