[css-font-loading] Add some issues about the phrase 'the document'.

Author: tabatkins

css-font-loading/Overview.bs

@@ -112,6 +112,9 @@ The <code>FontFace</code> Interface</h2>
 	Can we rename that value?
 	Media stuff uses "none", other APIs use "empty", "idle", "nothing".
 
+	Issue: Clarify all mentions of "the document" to be clear about which document is being referenced,
+	since objects can move between documents.
+
 	<div dfn-type=attribute dfn-for=FontFace>
 		: <dfn>family</dfn>
 		: <dfn>style</dfn>
@@ -401,6 +404,8 @@ Interaction with CSS’s ''@font-face'' Rule</h3>
 	any change made to a ''@font-face'' descriptor is immediately reflected in the corresponding {{FontFace}} attribute,
 	and vice versa.
 
+	Issue: When a FontFace is transferred between documents, it's no longer CSS-connected.
+
 	The internal {{[[Urls]]}} slot of the {{FontFace}} object is set to the value of the ''@font-face'' rule's 'src' descriptor,
 	and reflects any changes made to the 'src' descriptor.