add UPDF

[gogamid]

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Types of Changes

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• New addition to list
• Fixing bug in existing item in list
• Removing item from list
• Changing structure (organization) of list

Proposed Changes

Free PDF editor that makes it possible to read, annotate and edit PDFs, change text and images on Mac.

PR Checklist

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• I have read the CONTRIBUTING guide
• I have explained why this PR is important
• I have added necessary documentation (if appropriate)

Further Comments

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