Add chapter 025: Common Bash Errors and Fixes

[Nishika10]

This PR adds a new chapter (025) titled "Common Bash Errors and Fixes" to the eBook.

It covers the most frequent Bash scripting errors that beginners face, including:

• Permission issues
• Syntax mistakes
• Variable errors
• Loop mistakes
• Arithmetic errors

Each section includes:

• Error message
• Cause
• Fix
• Example
• Explanation

A practical example, “Loop Over Files”, is also included to demonstrate a common logical mistake.

This chapter aims to help readers write reliable and maintainable Bash scripts, improving their understanding and debugging skills.
Note: This PR is submitted as part of Hacktoberfest 2025 and contributes to the open-source Bash scripting guide.

[what-the-diff]

PR Summary

• Added a new informational guide
  A new file named 025-common-bash-errors-and-fixes.md was added to the repository.

• Introduction to common errors in Bash
  This markdown file provides a comprehensive guide on common errors that developers may encounter when working with Bash scripts.

• Covered topics
  The guide includes but not limited to the following errors: permission denied, bad interpreter or no file found, command not found, syntax error near unexpected token, unexpected end of file, variable not expanding, integer expression expected, bad substitution, file redirection permission denied, and script not found.

• Detailed explanation and code examples
  Each error type discussed includes a detailed explanation and code examples to help understand and replicate the issues.

• Practical examples and debugging tips
  The document includes practical examples of common mistakes that beginners often make, and debugging tips to help resolve these issues.

• Key takeaways highlighted
  Important takeaways on avoiding and fixing Bash scripting errors are highlighted for easy reference.

[bobbyiliev]

Looks good! Thank you!

[Nishika10]

Thank you for merging! Glad to contribute