RFR: 8368953: Document the reason why Serial/Parallel/G1 use zero as dirty card value [v2]

[Thomas Schatzl]

> Hi all,
> 
>   please review this trivial change to document the reason for the dirty/clean card value selection.
> 
> Testing: local compilation
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with two additional commits since the last revision:

 - Update src/hotspot/share/gc/shared/cardTable.hpp
 - Update src/hotspot/share/gc/shared/cardTable.hpp

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27575/files
  - new: https://git.openjdk.org/jdk/pull/27575/files/d103feb7..cef01833

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27575&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27575&range=00-01

  Stats: 5 lines in 1 file changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/27575.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27575/head:pull/27575

PR: https://git.openjdk.org/jdk/pull/27575