Update file creation guidelines in documentation

[ashis-baral]

Clarified restrictions on file names created via the web interface.

Why:

Closes: #45716

What's being changed (if available, include any code snippets, screenshots, or gifs):

Removed the outdated file name restriction guidance for files created via the web interface.

Check off the following:

• A subject matter expert (SME) has reviewed the technical accuracy of the content in this PR. In most cases, the author can be the SME. Open source contributions may require an SME review from GitHub staff.
• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the review environment.

[docs-bot]

This pull request may have been opened accidentally. I'm going to close it now, but feel free to check out our contribution guidelines, or raise an issue.

[github-actions]

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Table of review links

Note: Please update the URL for your staging server or codespace.

The table shows the files in the content directory that were changed in this pull request. This helps you review your changes on a staging server. Changes to the data directory are not included in this table.

Source	Review	Production	What Changed
repositories/working-with-files/managing-files/creating-new-files.md	fpt ghec ghes@ 3.22 3.21 3.20 3.19 3.18 3.17	fpt ghec ghes@ 3.22 3.21 3.20 3.19 3.18 3.17

Key: fpt: Free, Pro, Team; ghec: GitHub Enterprise Cloud; ghes: GitHub Enterprise Server

🤖 This comment is automatically generated.

[subatoi]

Apologies @ashis-baral: most of the PRs we receive of this nature (deleting content only) are spam. I'll try to refine the workflow so legitimate PRs like this aren't affected, but otherwise this looks good. Thanks for spotting and raising it!

[github-actions]

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