docs: add Sugar Activities guide (FLOSS Manuals) #21

[pan103769]

Adds the complete “Make Your Own Sugar Activities” guide from FLOSS Manuals as Markdown documentation.

Source: https://archive.flossmanuals.net/make-your-own-sugar-activities/
License: GPL-2.0-or-later

• Content preserved verbatim (no rewrites or summarization)
• Header hierarchy cleaned up and duplicate section titles removed
• Added under docs/ for direct in-repo reference and future use

issue: #21

[pan103769]

@quozl Could you please take a look
This PR addresses issue #21.

Note: I accidentally closed PR #39 while working on this, so this PR supersedes it.

[quozl]

What about the examples that were in the book?

[quozl]

Is this replaced by #41 ?

[pan103769]

yes , Superseded by #41, which contains the consolidated changes. closing this pr