Reviving for the sake of documenting a solution.
In order to disable escaping of HTML entities in a tag, use safeHTMLAttr, as previously suggested. However, the catch is that safeHTMLAttr should be used to mark the complete attribute (name + value), not just the value.
Original:
No escaping:
<meta name="description" {{ .Page.Description | printf "content=%q" | safeHTMLAttr }}>
Bear in mind that whenever you use the safe* functions (safeHTML, safeHTMLAttr, etc), it means you fully trust the input.
A malicious input could infect your website. Given a content file like this:
---
description: "Untrusted page's description. \"><script>alert('hello')</script>"
---
And a template:
<meta name="description" content="{{ .Description }}">
<meta name="description" {{ .Description | printf "content=%q" | safeHTMLAttr }}>
The output is:
<meta name="description" content="Untrusted page's description. "><script>alert('hello')</script>">
<meta name="description" content="Untrusted page's description. \"><script>alert('hello')</script>">
Notice that the original form escapes the script tag, and the form with safeHTMLAttr does not, thus outputting JavaScript that is executed on page load.