Update index.mdx

[swethaanbalagan]

fixed few typos

Lesson authoring peer review checklist:

• Includes authorship line: Text adaptation by [Name]
• The lesson has an informative/compelling description, fit for a preview on the home page.
• The lesson has no grammar/spelling errors
• The lesson has no mathematical errors
• The table of contents effectively conveys the overall structure of the lesson
• The lesson uses no # Top Level headings
• The lesson includes well-chosen comprehension questions
• The lesson incorporates the core visuals from the video
• The visuals are clear and helpful for understanding
• The components are used in the places and ways they are intended (see the readme)

Website change review checklist:

• I have requested a review from the appropriate persons
• I have checked that my changes work in the preview
• I have checked that the rest of the site is still functioning in the preview
• I have checked that my content/code is consistent with existing content/code
• I have used components in the places and ways they are intended (see the readme)
• I have formatted all of my code with Prettier

This pull request: