feat(glossy): use @term[supplement] to override term display

If you want to completely override how a term is displayed, you can pass
content in via the square brackets on the term's reference.

For example, a term @www which might normally display as "worldwide web
(WWW)" or something similar, could instead display as FOOBAR by using
@www[FOOBAR].

glossy/tests/override-display/test.typ

@@ -0,0 +1,33 @@
+#import "/lib.typ": *
+
+#let myGlossary = (
+  html: (
+    short: "HTML",
+    long: "Hypertext Markup Language",
+    description: "A standard language for creating web pages",
+    group: "Web"),
+  css: (
+    short: "CSS",
+    long: "Cascading Style Sheets",
+    description: "A language used for describing the presentation of a document",
+    group: "Web"),
+  tps: (
+    short: "TPS",
+    long: "test procedure specification",
+    description: "A document on how to run all the test procedures"),
+   unused: "Unused term, which shouldn't print in the glossary."
+)
+
+#show: init-glossary.with(myGlossary)
+
+#set page(height: auto, width: 6.5in, margin: 1em, numbering: "1")
+
+= Overriding term display
+
+Here is @html[HTML being overidden].
+
+Here is @css[] (blank).
+
+Here is @tps[TPS with #emph("content")]
+
+#glossary()