Fix typo in class comments ...

Fix #213

(cherry picked from commit 298febe695c31d107acb95a0b4b299a2040bd4bf)
[DOCS] Improve section on JDK requirement

Fix #226

(cherry picked from commit 6788a7163e90010c38baa3524827775ad4ee2594)
[DOC] Fix incorrect EsStorage package in Pig section

Fix #224

(cherry picked from commit e50abaeb6e4215296c6bf50d71298694c9cdc473)
[DOC] Clarify outcome of index operation

Fix #222

(cherry picked from commit c47f7e50f6b4fcd7af07efedff0e080366d98deb)