docs: clarify that internal adaptations of arc42 need not be published

[gernotstarke]

Clarifies LICENSE.txt so that companies understand that internal adaptations of the template never have to be published, and adds a link to https://arc42.org/license.

Why

Every license page repeated the Creative Commons deed sentence

If you remix, transform, or build upon material from arc42, you must distribute your contributions under the same license as the original.

Companies read that as "our internal customization has to be published". ShareAlike (CC BY-SA 4.0 §3(b)) only applies when adapted material is Shared, meaning provided to the public, so purely internal adaptation carries no publication duty at all.

What changed

• The ShareAlike sentence now names its trigger, sharing the result outside your own organization.
• A new section explains the situation for companies: adapt internally without publishing, attribution required when passing the template on, CC BY-SA applies to an adapted template only when it is published.
• Attribution is described as required on distribution and appreciated for internal use, which matches the license instead of overstating it.
• The scope of the license is stated explicitly: it covers the template, its structure, headings and explanatory text, not the architecture content written into it.

Wording is plain prose, no legal advice, and the Creative Commons text stays authoritative.

Companion PRs: arc42.org-site, arc42.de-site, faq.arc42.org-site, arc42-template.

🤖 Generated with Claude Code

https://claude.ai/code/session_01CDejMSpSy82t69XYBMyPY6