You should add a note about URL-encoding `|` as `%7C`

**Describe the issue**
Constructing a URL for an API call with multiple font family names can cause validation/parsing issues for a page.

**To Reproduce**
A link such as this one:

`
`

Can produce the validation error:

>Bad value [https://fonts.googleapis.com/css?family=UnifrakturMaguntia|Kalam|Noto+Music&display=swap](https://fonts.googleapis.com/css?family=UnifrakturMaguntia%7CKalam%7CNoto+Music&display=swap) for attribute href on element [link](https://html.spec.whatwg.org/multipage/#the-link-element): Illegal character in query: | is not allowed.

**Expected behavior**
A note that explains that the safest way to call the API for all situations is to URL-encode the `|` character as `%7C`.

**Additional context**
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**Screenshots**
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