[close #610] [to #590] add docs for api v2 and tls reload (#611)

[ti-srebot]

cherry-pick #611 to release-3.3
You can switch your code base to this Pull Request by using git-extras:

# In client-java repo:
git pr https://github.com/tikv/client-java/pull/614

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/client-java.git pr/614:release-3.3-7e6af2984de1

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Signed-off-by: iosmanthus myosmanthustree@gmail.com

What problem does this PR solve?

Issue Number: close #610, to #590

Related changes

• Need to cherry-pick the release branch

[ti-srebot]

/run-all-tests

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-3.3@64beacf). Click here to learn what that means.
The diff coverage is n/a.

@@              Coverage Diff               @@
##             release-3.3     #614   +/-   ##
==============================================
  Coverage               ?   34.56%           
  Complexity             ?     1413           
==============================================
  Files                  ?      278           
  Lines                  ?    17352           
  Branches               ?     1971           
==============================================
  Hits                   ?     5997           
  Misses                 ?    10746           
  Partials               ?      609           

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[iosmanthus]

LGTM