RFR: Section on PRs [v2]

[Jesper Wilhelmsson]

> Some tips for creating pull requests.

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

  Added sentence about keeping PR up to date

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Changes:
  - all: https://git.openjdk.java.net/guide/pull/79/files
  - new: https://git.openjdk.java.net/guide/pull/79/files/61f94e82..07c33db1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=guide&pr=79&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=guide&pr=79&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/guide/pull/79.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/79/head:pull/79

PR: https://git.openjdk.java.net/guide/pull/79