Add Draft Pull Request glossary card

[Aniket-The-TechWhiz]

Description

This PR adds a new glossary card for Draft Pull Request in the GitHub section.

Changes made

• Added a new "Draft Pull Request" glossary card.
• Explained what a Draft PR is and when to use it.
• Mentioned that Draft PRs cannot be merged until they are marked as ready for review.
• Included tags: draft, WIP, and feedback.
• Set data-cat="github" so the card appears under the GitHub filter and in search results.

Why

New contributors often hesitate to open a pull request because they think it has to be complete. This glossary entry introduces Draft Pull Requests as a way to share work in progress, get early feedback, and signal that the work is not yet ready for review.

[Ayushmore1214]

Nice write-up on the card @Aniket-The-TechWhiz, the definition reads well and the data-cat="github" is correct. One blocker before merge:

Your commit is missing the DCO sign-off. This repo requires every commit to carry a Signed-off-by: line (see CONTRIBUTING.md). Your intro PR had it, this one doesn't. Fix it with:

git commit --amend -s --no-edit
git push --force-with-lease

Also a small nit while you're in there: the <div class="card-top">, <h2>, <p> and <ul> inside your new <article> are indented one level less than the surrounding cards. Matching the neighbours keeps the file tidy.

Once that's pushed the DCO check will go green and I'll merge. This closes #52.