RFR: Minor cleanups after the JBS re-write [v2]

[Jesper Wilhelmsson]

> Using markdown tables instead of html tables.
> Added a separate style for JBS values.
> Minor language fixes to make it the same style as the rest of the guide.
> Clarified some sentences.
> Added the label jep-superseded to the dictionary.

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

  Updated text to accomodate for backports to feature relseases in rampdown

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Changes:
  - all: https://git.openjdk.org/guide/pull/106/files
  - new: https://git.openjdk.org/guide/pull/106/files/1d43f369..afc14900

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=guide&pr=106&range=01
 - incr: https://webrevs.openjdk.org/?repo=guide&pr=106&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/guide/pull/106.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/106/head:pull/106

PR: https://git.openjdk.org/guide/pull/106