Add a mechanism to ignore some patterns in gotemplate/razor

[jocgir]

This pull request includes several updates to the gotemplate project, focusing on upgrading dependencies, adding new features, and improving documentation. The most important changes include updating the Hugo version in the GitHub workflows, adding a new flag for ignoring Razor expressions, and enhancing the template package with new functionalities and comprehensive documentation.

Dependency Updates:

• .github/workflows/build.yml and .github/workflows/pr.yml: Updated Hugo version from 0.82.0 to 0.135.0. [1] [2]
• docs/themes/book: Updated submodule commit reference.

New Features:

• main.go: Added ignore-razor flag to the runGotemplate function. [1] [2]
• template/razor.go: Implemented logic to handle ignored Razor expressions in applyRazor method.
• template/razor_test.go: Added tests for ignored Razor expressions and an example function. [1] [2]

Documentation Enhancements:

• template/template.go: Added detailed package-level documentation and comments for new and existing methods. [1] [2] [3] [4]

Miscellaneous:

• render-doc: Added environment variable GOTEMPLATE_NO_STDIN to the cleanup function in order to avoid nagging errors while executing gotemplate without having access to the stdin.

[jonapich]

Is there any way we can add an example about how to use it (and probably show regex vs non-regex too)?