4.2: a link's brackets balance inside a directive's content

spec/flavour.md

@@ -129,9 +129,11 @@ quoted where bare carries it, an escape longer than it need be, an empty `{attrs
 each a named error naming the spelling to write instead.
 
 **Escaping**: the emitter backslash-escapes whatever literal text would otherwise parse as
-directive syntax — the leading `:` of a would-be directive, `]` inside content, a `{` right
-after a directive's closing `]`, which would otherwise be read as the attributes it has none
-of; outside code spans and code blocks, a backslash before `:` in input yields a literal colon.
+directive syntax — the leading `:` of a would-be directive, `]` inside content, a bracket a link's
+destination and title inside content leave unbalanced (an autolink holding one takes the
+`[text](url)` form), a `{` right after a directive's closing `]`, which would otherwise be read as
+the attributes it has none of; outside code spans and code blocks, a backslash before `:` in input
+yields a literal colon.
 
 **Malformed directives are error results**, named: an unclosed container at end of input, a body
 fence line of the container's length or longer, a bare colon-run line outside any container or