docs: update examples and tips on commit statistics

[ognis1205]

Description

This PR updates the example templates and adds a new tips & tricks section showcasing how to use statistics in git-cliff templates. It demonstrates how to include commit counts, durations, issue references, and other metrics in the generated changelog. Closes #1160

Motivation and Context

The usage of the statistics object is currently under-documented, which may prevent users from utilizing it effectively in their templates. This PR addresses that gap by adding practical examples and tips to help users take advantage of the available data in a meaningful way.

How Has This Been Tested?

N/A

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (no code change)
• Refactor (refactoring production code)
• Other

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have formatted the code with rustfmt.
• I checked the lints with clippy.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 41.92%. Comparing base (6db7d49) to head (719c8be).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1162   +/-   ##
=======================================
  Coverage   41.92%   41.92%           
=======================================
  Files          21       21           
  Lines        2009     2009           
=======================================
  Hits          842      842           
  Misses       1167     1167           

Flag	Coverage Δ
unit-tests	41.92% <ø> (ø)

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[ognis1205]

@orhun

Thanks for the review! I’ll make the changes as per your suggestions and ping you again once they’re ready.

[ognis1205]

Hey @orhun,

I’ve addressed all the points that were raised in the review.
Let me know if there’s anything else you’d like me to revise or clarify.
Also, please review #1151 together with this one when you have a chance.

Thanks!

[orhun]

This is blocked by #1151