RFR: Update affects_versions.svg

[Alexey Ivanov]

Update `affects_versions.svg` as per discussion in #149.

1. Make the arrows look better, narrower;
2. Put red cross for version 8 in the case 5 to make it explicit the issue won't be backported to both 11u and 8u;
3. Move all text a few pixels down, closer to the timeline;
4. Left-align `12-na` and `11-wnf` in cases 4 and 5 and display closer to 11 LTS line;
5. Reduce the circle radius for where an issue is fixed;
6. Mark-up 8 as LTS (displayed in bold).

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Commit messages:
 - Markup 8 as LTS
 - Left-align 12-na and 11-wnf; close to LTS line
 - Align the middle of 11-wnf with 12-na
 - Reduce the circle radius
 - Reformat <use> for red cross
 - Move 11-wnf to the right, matching - over cross
 - Ensure copy of the cross uses 2-pixel stroke
 - Move timeline text 2-pixel down
 - Move 12-na to the middle of its own line
 - Make the arrow narrower
 - ... and 1 more: https://git.openjdk.org/guide/compare/71fbb94b...13ebe135

Changes: https://git.openjdk.org/guide/pull/153/files
  Webrev: https://webrevs.openjdk.org/?repo=guide&pr=153&range=00
  Stats: 19 lines in 1 file changed: 5 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/guide/pull/153.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/153/head:pull/153

PR: https://git.openjdk.org/guide/pull/153