・Change "RC6" to "RCBugFix" on top part of the readme
・Unify distribution date of RCBugFix and RC6
・Move comments about IDE version from RCBugFix section to RC6 section

It sync with the RC.

follow-up to commit 200b2487

Update release date in another place

Oops! at least 1.6.0

* Description for RC5
* Hint for deprecated Arduino versions

Added my name following naming convention.

Discussion at #2541

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