chore(docs): Pre-encoded unicode characters can't be used in paths

[Auspicus]

Description

I ran into this weird behavior when creating a multilingual site where the paths were coming pre-encoded from the CMS. I was expecting that Gatsby would recognise pre-encoded paths and make the necessary adjustments so that I wouldn't have to handle anything in gatsby-node but I later found that paths MUST be encoded or pages break and bad things happen :o

I think this could be changed internally so that we don't have to rely on the developer to pass the correct value and instead handle the encoding inside Gatsby. For the meantime however, a docs update should suffice so that developers don't have to dig into the internals to understand whether or not unicode is supported and how to use it.

TLDR; Made a few changes to the API docs to mention how paths should not be encoded when containing unicode characters.

Documentation

• Add a section into the path field description in createPage API
• Add a section in the routing docs explaining that path is not expected to be encoded

Related Issues

Related to #16765

[Auspicus]

@LekoArts I went ahead and updated the docs to note the way that createPage is currently expecting the path param to not be encoded based on that old ticket: #16765. Is this the right direction or should there be a change to the API to support encoded paths?

[LekoArts]

Thanks!