Update index.mdx Spelling errors from discription to description

[Matsukami7]

Update index.mdx Spelling errors from discription to description

Summary

Screenshots (optional)

Documentation checklist

• The documentation style guide has been adhered to.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.