Fix typos and markdown formatting

[jay-tau]

Changes Summary

• Fixed repeated word in contributors guide ("Markdown markdown" → "Markdown is")
• Corrected markdown link syntax in MFs FAQ ([text] → (link))

Impacted Files

1. contributors/index.md
2. faqs/mfs/why-are-index-funds-in-india-not-as-cheap-as-vanguards-index-funds-and-etfs.md

Verification Checklist

• [x] Confirmed markdown renders correctly in GitHub preview
• [x] Checked link functionality
• [x] Verified no unintended formatting changes

Reviewer Notes

• Changes maintain original content meaning
• Improves readability without altering technical content

[cla-bot[bot]]

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[jay-tau]

@cla-bot, I accept the CLA.