Update index.md to remove duplicate macro

[ronabop]

Removing duplicate entry display for https://falco.org/docs/reference/rules/default-macros/#file-system-object-removed

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind user-interface

/kind content

/kind translation

/kind event

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area blog

/area documentation

/area community

What this PR does / why we need it:

Cleanup of web/display duplicaton

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

[poiana]

Welcome @ronabop! It looks like this is your first PR to falcosecurity/falco-website 🎉

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: LucaGuerra, ronabop

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Needs approval from an approver in each of these files: - ~~[content/OWNERS](https://github.com/falcosecurity/falco-website/blob/master/content/OWNERS)~~ [LucaGuerra] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[poiana]

LGTM label has been added.

Git tree hash: e0e627c6b923ff6510fba808b0e5b2adef004a49