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ARROW-7277: [Java] [Doc] Add discussion about vector lifecycle

As discussed in https://issues.apache.org/jira/browse/ARROW-7254?focusedCommentId=16983284&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16983284, we need a discussion about the lifecycle of a vector.

Each vector has a lifecycle, and different operations should be performed in particular phases of the lifecycle. If we violate this, some unexpected results may be produced. This may cause some confusion for Arrow users. So we want to add a new section to the prose document, to make it clear and explicit.

Closes #5969 from liyafan82/fly_1203_doc and squashes the following commits:

48be293be <liyafan82>  Resolve comments
3ad95de57 <liyafan82>  Fix styles for other Java documents
030d9da85 <liyafan82>  Add discussion about vector lifecycle

Authored-by: liyafan82 <fan_li_ya@foxmail.com>
Signed-off-by: Micah Kornfield <emkornfield@gmail.com>