fixups: typo and clarified basic.compound.invalid.pointer

Author: joshuaberne

source/ub.tex

@@ -311,8 +311,11 @@
 \ubxref{basic.compound.invalid.pointer] \\
 Indirection or
 the invocation of a deallocation function
-with an invalid pointer value
+with a pointer value referencing storage
+that has been freed
 has undefined behavior.
+(Most other uses of such a pointer have
+implemention-defined behavior.)
 
 \pnum
 \begin{example}
@@ -632,7 +635,7 @@
 
 \pnum
 \ubxref{conv.member.missing.member} \\
-The conversino of
+The conversion of
 a pointer to a member of a base class
 to a pointer to member of a derived class
 that coudl not contain that member