RFR: Remove legacy section on mercurial [v2]

[Jesper Wilhelmsson]

> Mercurial is no longer used in the OpenJDK project.

Jesper Wilhelmsson has updated the pull request incrementally with one additional commit since the last revision:

  One more place

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

Changes:
  - all: https://git.openjdk.org/guide/pull/127/files
  - new: https://git.openjdk.org/guide/pull/127/files/9af2de41..91cd30b6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=guide&pr=127&range=01
 - incr: https://webrevs.openjdk.org/?repo=guide&pr=127&range=00-01

  Stats: 22 lines in 2 files changed: 4 ins; 17 del; 1 mod
  Patch: https://git.openjdk.org/guide/pull/127.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/127/head:pull/127

PR: https://git.openjdk.org/guide/pull/127