RFR: 8275783: G1: fix incorrect region type documentation in HeapRegionType

[Albert Mingkun Yang]

On Fri, 22 Oct 2021 10:12:00 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Trivial change of fixing documentation.

Thanks for the review.

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PR: https://git.openjdk.java.net/jdk/pull/6079