Regex/move and improve

[WillemZeiler]

PR Description:

In this PR:
TLDR: Regex was in the wrong place -> Moved it. While at it, I also improved the script and readme.

Create folder and readme.md

• Created sub-folder "Check for special characters" in the Regular Expressions folder.
• Created a new readme.
• Removed the old folder and old readme.

Update and rename specialcharacter.js to specialcharacter.js

• Moved the script to the new created folder in Regular Expressions.
• Refactored/fixed the code:
  -- Renamed regex variable to disallowedChars for clarity.
  -- Escaped special characters inside the regex to correctly match (, ), [, and ].
  -- Added detailed comments explaining the purpose and structure of the regular expression.
  -- Replaced placeholder field name with a variable for easier reuse and readability.
  -- Improved error messaging to clearly inform users about invalid input.

Update readme.md
Expanded and clarified the Readme. Also included in the description the updated script.

Pull Request Checklist

Overview

• Put an x inside of the square brackets to check each item.
• I have read and understood the CONTRIBUTING.md guidelines
• My pull request has a descriptive title that accurately reflects the changes and the description has been filled in above.
• I've included only files relevant to the changes described in the PR title and description
• I've created a new branch in my forked repository for this contribution

Code Quality

• My code is relevant to ServiceNow developers
• My code snippets expand meaningfully on official ServiceNow documentation (if applicable)
• I've disclosed use of ES2021 features (if applicable)
• I've tested my code snippets in a ServiceNow environment (where possible)

Repository Structure Compliance

• I've placed my code snippet(s) in one of the required top-level categories:
  • Core ServiceNow APIs/
  • Server-Side Components/
  • Client-Side Components/
  • Modern Development/
  • Integration/
  • Specialized Areas/
• I've used appropriate sub-categories within the top-level categories
• Each code snippet has its own folder with a descriptive name

Documentation

• I've included a README.md file for each code snippet
• The README.md includes:
  • Description of the code snippet functionality
  • Usage instructions or examples
  • Any prerequisites or dependencies
  • (Optional) Screenshots or diagrams if helpful

Restrictions

• My PR does not include XML exports of ServiceNow records
• My PR does not contain sensitive information (passwords, API keys, tokens)
• My PR does not include changes that fall outside the described scope

[ivan-betev]

Looks good!