KAFKA-4208; Add record headers upgrade doc
KAFKA-4208; Add record headers upgrade doc

Update upgrade.html

Raising this now, as KIP-118 is pulled from release as such submitting this without java 8 changes.

As per remaining review comment from https://github.com/apache/kafka/pull/2772, updating the upgrade notes.

Author: Michael André Pearce <michael.andre.pearce@me.com>
Author: Michael Andre Pearce <Michael.Andre.Pearce@me.com>

Reviewers: Jiangjie Qin <becket.qin@gmail.com>, Ismael Juma <ismael@juma.me.uk>

Closes #2991 from michaelandrepearce/KIP-82

lindong28/kafka,TiVo/kafka,Esquive/kafka,apache/kafka,Ishiihara/kafka,KevinLiLu/kafka,KevinLiLu/kafka,sslavic/kafka,mihbor/kafka,guozhangwang/kafka,sebadiaz/kafka,Chasego/kafka,themarkypantz/kafka,ErikKringen/kafka,sslavic/kafka,guozhangwang/kafka,Esquive/kafka,gf53520/kafka,mihbor/kafka,mihbor/kafka,richhaase/kafka,MyPureCloud/kafka,TiVo/kafka,airbnb/kafka,KevinLiLu/kafka,noslowerdna/kafka,airbnb/kafka,noslowerdna/kafka,sslavic/kafka,Ishiihara/kafka,themarkypantz/kafka,MyPureCloud/kafka,Chasego/kafka,ErikKringen/kafka,apache/kafka,airbnb/kafka,mihbor/kafka,noslowerdna/kafka,lindong28/kafka,MyPureCloud/kafka,gf53520/kafka,TiVo/kafka,lindong28/kafka,Ishiihara/kafka,guozhangwang/kafka,sebadiaz/kafka,KevinLiLu/kafka,Chasego/kafka,Esquive/kafka,gf53520/kafka,sslavic/kafka,themarkypantz/kafka,richhaase/kafka,themarkypantz/kafka,Esquive/kafka,ollie314/kafka,sebadiaz/kafka,airbnb/kafka,ollie314/kafka,Ishiihara/kafka,ollie314/kafka,sebadiaz/kafka,richhaase/kafka,richhaase/kafka,apache/kafka,ErikKringen/kafka,MyPureCloud/kafka,noslowerdna/kafka,TiVo/kafka,ErikKringen/kafka,guozhangwang/kafka,apache/kafka,gf53520/kafka,lindong28/kafka,Chasego/kafka,ollie314/kafka