Document file name and title are inconsistent

[Yimismi]

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https://github.com/apache/skywalking/blob/master/docs/en/protocols/Trace-Data-Protocol-v3.md
the file name is Trace-Data-Protocol-v3 while its title is Trace Data Protocol v2. it's confusing.

[wu-sheng]

That is dev doc. :) We are upgrading many things in the master branch and incoming 8.x.

Read this, #4599 and the mail list link. You will have more informantion.