[docs] Update encodings section
[docs] Update encodings section

With KUDU-100 and KUDU-1751 we need to update our encodings docs.

Change-Id: Ic445c18807c5bdb065575b2f4034420c659fde6e
Reviewed-on: http://gerrit.cloudera.org:8080/5966
Tested-by: Kudu Jenkins
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@apache.org>

cloudera/kudu,InspurUSA/kudu,andrwng/kudu,InspurUSA/kudu,andrwng/kudu,InspurUSA/kudu,helifu/kudu,cloudera/kudu,EvilMcJerkface/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,cloudera/kudu,helifu/kudu,andrwng/kudu,andrwng/kudu,cloudera/kudu,cloudera/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,helifu/kudu,EvilMcJerkface/kudu,cloudera/kudu,helifu/kudu,helifu/kudu,EvilMcJerkface/kudu,andrwng/kudu,helifu/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,andrwng/kudu,helifu/kudu,EvilMcJerkface/kudu,andrwng/kudu,cloudera/kudu,InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,andrwng/kudu,andrwng/kudu