docs: add documentation style guide for community and AI-assisted contributions

[kenvandine]

Summary

• Adds docs/dev/documentation.md — a style guide covering writing principles,
  voice and tone, document structure by type (concept, how-to, API reference,
  integration guide), formatting conventions (code blocks, tables, callouts,
  status badges, collapsible sections), file/directory layout, and templates
  contributors can copy directly.
• Adds a specific section on AI-assisted contributions: a failure-mode table
  and a pre-submission checklist so AI-drafted docs meet the same accuracy bar
  as hand-written ones.
• Small edits to docs/dev/README.md and docs/dev/contribute.md to link the
  new guide from the developer hub and the existing AI Policy section.

Why

Documentation guidance was previously distributed across AGENTS.md,
contribute.md, and philosophy.md without a single place that answered "how
should I write a doc?" The guide pulls these threads together and adds concrete
formatting conventions derived from the existing ~58 doc files.

Test plan

• All internal links in docs/dev/documentation.md resolve correctly.
• Links from README.md and contribute.md to the new guide are correct.
• Style and tone are consistent with existing guide docs.
• No build artifacts or code changes included.

[fl0rianr]

Very Nice! One small site-navigation note: should dev/documentation.md also be added to mkdocs.yml under Development? Right now the new page is linked from docs/dev/README.md, but it does not appear in the sidebar nav.

[jeremyfowers]

Very Nice! One small site-navigation note: should dev/documentation.md also be added to mkdocs.yml under Development? Right now the new page is linked from docs/dev/README.md, but it does not appear in the sidebar nav.

Yes all new docs, including this one, should be added to mkdocs.yml nav.

[jeremyfowers]

This will be a very nice document to have! Please see review feedback.

[kenvandine]

All review feedback addressed in the latest commit (346a199):

fl0rianr:

• Added sidebar nav entry to mkdocs.yml
• Added table of contents (doc's own 5+ H2 rule applies here)
• Fixed both nested fenced code block examples to use 4-backtick outer fences
• Added Lossy rewriting and Slop-style writing rows to the AI failure-mode table
• Added preservation-during-rewrites checklist item

jeremyfowers:

• Renamed ### Automate the documentation away → ### Simplify instead of documenting
• Changed ### The reader is a capable adult → ### The reader is capable
• Clarified pronoun rule for developer-docs context (when "the user" is the developer's end-user)
• Updated Voice/Tone table: stricter humor rule, added Figures of speech and Marketing language rows
• Revised tab/variant rule to prefer tabs even for small per-platform differences (copy-pastable snippets)
• Softened the two-item table rule to allow judgment
• Made inline formatting examples consistently escaped
• Expanded CLI-commands checklist item to cover curl commands and test scripts
• Replaced overly-specific sentence-opener item with a broader style/slop-patterns item
• Broadened code-examples item to cover all executable content
• Replaced vague length item with a specific cut-criteria rule
• Consolidated Community Contribution Process: removed redundant ### Before you start sub-heading, merged Review expectations + Maintainer for documentation into a single ### Review and ownership section
• Updated maintainer to @jeremyfowers per suggested text

[fl0rianr]

Thanks @kenvandine! This is very close. If I got it right wo small items Jeremy mentioned still look unresolved to me before I approve:

1. The checklist still says “All links resolve to real pages.” I’d prefer the more specific wording:
   “All internal links, anchors, external links, and referenced files resolve correctly.”

2. The Quick Reference still says “Using a table for 2 items”, which seems to contradict the updated Tables section. Maybe:
   “Using a table when a sentence or list would be clearer | Use a sentence or list instead”

After that this looks good to me.

[kenvandine]

Both addressed in 3726df6:

1. Checklist item updated to "All internal links, anchors, external links, and referenced files resolve correctly."
2. Quick Reference row updated to "Using a table when a list or sentence would be clearer | Use a sentence or list instead"

[fl0rianr]

Thanks! You have my go, but I think you should have @jeremyfowers give the opportunity as well.