3d-ascii-viewer: add page

[tango8]

Checklist

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR contains at most 5 new pages.
• The PR is authored by me, or has been human-reviewed if it was created with AI or machine translation software.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known): 1.4.0
• Reference issue: #

[CLAassistant]

All committers have signed the CLA.

[tldr-bot]

The build for this PR failed with the following error(s) at commit
01448e0d8044d98ed200fad0366b789be585747a:

pages/common/3d-ascii-viewer.md:
Error: Parse error on line 28:
...-viewer {{{--help}}`y`
-----------------------^
Expecting 'NEWLINE', 'TEXT', 'DASH', 'BACKTICK', got 'COMMAND_TEXT'
pages/common/3d-ascii-viewer.md:27: TLDR103 Command example is missing its closing backtick

Please fix the error(s) and push again.

[ivanbaluta]

Thanks for the contribution!