Consolidate the Hugo Pipes section into a single page

[jmooring]

At one point in time the pages in the Hugo Pipes section were the only place where we documented js.Build, css.Sass, resources.FromString, etc. Today, every function and method to capture or process a resource has its own page, so the Hugo Pipes section is a bit redundant.

To avoid maintaining the same content in two places, we've already changed the following to refer to the page dedicated to the relevant function:

• /hugo-pipes/bundling/ => functions/resources/concat/
• /hugo-pipes/fingerprint/ => functions/resources/fingerprint/
• /hugo-pipes/js/ => /functions/js/
• /hugo-pipes/minification/ => /functions/resources/minify/
• /hugo-pipes/postcss/ => /functions/css/postcss/
• /hugo-pipes/postprocess/ => /functions/resources/postprocess/
• /hugo-pipes/resource-from-string/ => /functions/resources/fromstring/
• /hugo-pipes/resource-from-template/ => /functions/resources/executeastemplate/
• /hugo-pipes/transpile-sass-to-css/ => /functions/css/sass/

I think that one page, perhaps in the content management section, that explains the general concept is important:

• What's a resource?
• How do you capture one?
• What can you do with it?

I have used the term "asset pipeline" instead of Hugo Pipes elsewhere in the documentation and in the project's README. The intent was to make the concept clear using a generic term/phrase instead of a branded feature name.

I don't have a strong opinion either way, but I'm inclined to use the title "Asset pipelines" for the consolidated page.