[expr.prim.lambda.general] Added missing definition for the term "lambda".

Co-authored-by: Johel Ernesto Guerrero Peña <[email protected]>

Author: Bekenn

source/expressions.tex

@@ -1843,8 +1843,9 @@
 \end{example}
 
 \pnum
-A lambda is a \defn{generic lambda}
-if the \grammarterm{lambda-expression}
+A \grammarterm{lambda-expression} is a \defn{lambda}.
+A lambda is \defnx{generic}{lambda!generic}
+if the \grammarterm{parameter-declaration-clause}
 has any generic parameter type placeholders\iref{dcl.spec.auto}, or
 if the lambda has a \grammarterm{template-parameter-list}.
 \begin{example}
@@ -2059,7 +2060,7 @@
 \end{note}
 
 \pnum
-The closure type for a non-generic \grammarterm{lambda-expression} with no
+The closure type for a non-generic lambda with no
 \grammarterm{lambda-capture}
 whose constraints (if any) are satisfied
 has a conversion function to pointer to