RFR: Clearly state that users should create branch [v2]

[Magnus Ihse Bursie]

> A recent PR submission to the JDK made me aware that the guide does not strongly enough emphasize the importance of creating a separate branch. 
> 
> (If you do put your changes directly in `master`, the Skara bots will put up harsh warnings, which is not a nice way to welcome someone who has tried to do everything right, including reading the guide)

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  Fix typo
  
  Co-authored-by: Alexey Ivanov <alexey.ivanov at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/guide/pull/94/files
  - new: https://git.openjdk.org/guide/pull/94/files/aa8e02c6..17d06e30

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=guide&pr=94&range=01
 - incr: https://webrevs.openjdk.org/?repo=guide&pr=94&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/guide/pull/94.diff
  Fetch: git fetch https://git.openjdk.org/guide pull/94/head:pull/94

PR: https://git.openjdk.org/guide/pull/94