misc/gimp-help-en: update 2.10.0 → 2.10.34

2.10.34 User Manual Source (Release Date: 2023-03-05)
https://docs.gimp.org/download.html#gimp-210-latest

• Fix MASTER_SITES.
• Add default option QUICKREFERENCE for "Generate GIMP Quickreference PDF".
• Prepare for slave ports with other languages.

PR: 280095
Approved by: liangtai.s16@gmail.com (maintainer, timeout 14 days)