[temp] Fix confusion between two different forms of template-declaration.

When the template-head is followed by a concept-definition, it is not
technically followed by a declaration, so avoid claiming that it is.

Author: zygoloid

source/templates.tex

@@ -68,6 +68,7 @@
 \grammarterm{declaration}
 in a
 \grammarterm{template-declaration}
+(if any)
 shall
 
 \begin{itemize}
@@ -80,18 +81,16 @@
 
 \item be a \grammarterm{deduction-guide}, or
 
-\item be an \grammarterm{alias-declaration}, or
-
-%%% FIXME: This is obviously wrong; a concept-definition is not a declaration.
-\item be a \grammarterm{concept-definition}.
+\item be an \grammarterm{alias-declaration}.
 \end{itemize}
 
 A \grammarterm{template-declaration} is a \grammarterm{declaration}.
 \indextext{template!definition of}%
 A \grammarterm{template-declaration} is also a definition
-if its \grammarterm{declaration}
-%%% FIXME: This is wrong, a concept-definition is not a declaration.
-either is a \grammarterm{concept-definition} or
+if its
+\grammarterm{template-head} is followed by
+either a \grammarterm{concept-definition} or
+a \grammarterm{declaration} that
 defines a function, a class, a variable, or a
 static data member. A declaration introduced by a template declaration of a
 \indextext{variable template!definition of}%