Adds config files to check spelling in incoming PRs

[eshanrnh]

📋 Description

Added config files to check for spelling in incoming PRs.

How to test:

1. Add the following files to your forked repo:

.github/styles/UmbracoSpelling/Spelling.yml 
.github/styles/config/dictionaries/en_US.aff 
.github/styles/config/dictionaries/en_US.dic 
.github/styles/config/dictionaries/umbraco.aff 
.github/styles/config/dictionaries/umbraco.dic

2. Create a PR with spelling issues.
3. The typos should show an inline comment like below:

📎 Related Issues (if applicable)

✅ Contributor Checklist

I've followed the Umbraco Documentation Style Guide and can confirm that:

• Code blocks are correctly formatted.
• Sentences are short and clear (preferably under 25 words).
• Passive voice and first-person language (“we”, “I”) are avoided.
• Relevant pages are linked.
• All links work and point to the correct resources.
• Screenshots or diagrams are included if useful.
• Any code examples or instructions have been tested.
• Typos, broken links, and broken images are fixed.

Product & Version (if relevant)

Deadline (if relevant)

Anytime

📚 Helpful Resources

• 🧾 Umbraco Contribution Guidelines
• ✍️ Umbraco Documentation Style Guide

[eshanrnh]

If the message is not clear, there are other options too:

• "'%s' is a typo!"
• "Did you really mean '%s'?"

Any other suggestion?