Issue #3143 – fixed format conversion docs link

[Makefolder]

Description

Brought back the Format conversion documentation. The documentation of this feature was removed in commit 49c458b (May 20th, 2024) and was supposed to appear in the repository's wiki.

• Fixes syft convert: broken link in help - documentation no longer existing #3143

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Documentation (updates the documentation)
• Chore (improve the developer experience, fix a test flake, etc, without changing the visible behavior of Syft)

Checklist:

• I have added unit tests that cover changed behavior
• I have tested my code in common scenarios and confirmed there are no regressions
• I have added comments to my code, particularly in hard-to-understand sections