Review and update Danish translation - sync with English source

[Copilot]

This PR reviews and updates the Danish translation files to align with the current English source content, addressing several inconsistencies and outdated references.

Changes Made

i18n/da.po Updates

• Updated forum structure: Replaced outdated mailing list terminology with modern forum-based approach
  • Added translations for "NTP Pool Forum", "News site", "Development"
  • Updated descriptions to reflect forum vs mailing list usage
• Improved translations:
  • "The mailing lists" → "Fællesskab" (Community) to match English "Community"
  • Fixed typo: "Yderlig links" → "Yderligere links" (Additional links)
• Modernized content descriptions: Updated forum and development descriptions to match current English structure

docs/ntppool/da/homepage/intro.html Updates

• Updated hosting provider: Changed outdated Packet/NetActuate references to current Equinix Metal
• Improved Danish grammar and terminology:
  • Better word spacing and compound words ("tids servere" → "tidsservere")
  • More accurate numbers ("millioner eller tusind millioner" → "hundreder af millioner")
  • Clearer terminology ("statisk ip" → "statisk IP-adresse")
• Updated community references: Changed "mail listerne" (mailing lists) to "projektets fællesskabsforum" (project community forum)
• Consistent link text: Updated "her" → "tilgængelig" for better context

Impact

These changes ensure the Danish translation accurately reflects the current English content and structure, providing Danish users with up-to-date and properly translated information about the NTP Pool project.

Fixes #258.

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