docs(brand-kit): README polish and editorial style guide fixes

[Dragboyz]

What changed? Why?

• README: fixed shields to base/brand-kit, switched Brand Guide link to https, improved alt text, added Directory structure/How to use/Do not/Licensing/Download sections for clarity and accessibility.
• Editorial style guide: corrected punctuation/quotes (smart quotes, em dashes), fixed Oxford comma examples, cleaned ampersand examples, corrected Purdue OWL “Plain Style” URL, minor grammar/consistency tweaks.
• Goal: improve accuracy, accessibility, and contributor usability without altering brand policy.

Notes to reviewers

• Scope is docs-only; no asset or file renames.
• No content policy changes; examples and links made consistent with current guidance.
• If desired, I can add a .gitattributes line for PDFs (*.pdf -text) in a follow‑up to avoid editor EOL warnings.

How has it been tested?

• Rendered Markdown locally (headings, lists, tables, images).
• Verified external links resolve; switched http→https where applicable.
• Checked image paths case and existence in logo/.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2

[mehrdadmz70]

how can commit projects?