Add PeakURL docs

[Abd-Ur-Rehman]

This adds the initial peakurl/ docs payload for a proposed Docker Official Image.

PeakURL is an upstream-maintained, MIT-licensed, self-hosted URL shortener and branded links platform.

Included here:

• README-short.txt
• content.md
• compose.yaml
• github-repo
• license.md
• maintainer.md
• metadata.json
• logo.svg

Notes:

• the docs are written for the proposed official image name peakurl
• the content matches the current upstream container behavior from PeakURL/containers
• the app is intended to run with an external MySQL container and optional reverse-proxy TLS termination
• the image stores the full app tree in /var/www/html, so the docs explicitly explain how dashboard updates and image updates interact

Upstream repos:

• image repo: https://github.com/PeakURL/containers
• application repo: https://github.com/PeakURL/PeakURL