Add Hugo resources example

[rodrigoalcarazdelaosa]

Description

This PR adds an example for caching the resources folder in Hugo builds.

Motivation and Context

Caching the resources folder greatly reduces the building time in Hugo, specially for sites with lots of images.

How Has This Been Tested?

In my own tests, building time is reduced from 4–5 minutes to less than 1 minute. Reducing processing times is always good, at least for the planet 🌱🌍.

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)
• [x] Documentation (add or update README or docs)

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.