fix(tools): correct extension error message and format string in asciidoclint

[Devansh-567]

Description

Fixes a copy-paste error string and an unformatted print bug in the asciidoclint.py tooling script.

The script validates files ending with an .adoc extension, but the error message incorrectly stated that the file was missing an .mdk extension. Additionally, the original print statement did not call .format(f), meaning the actual file path was never injected into the string.

Changes

• Updated the error string to correctly reference .adoc.
• Appended .format(f) to ensure the target filename is printed when the validation fails.

How Has This Been Tested?

• Verified the script output locally with an invalid file extension to ensure it prints the correct error string along with the targeted filename without crashing.