P3923R0: Re NB US 145-234 (C++26 CD)

Fixes NB US 145-234 (C++26 CD).

Author: eisenwave

source/containers.tex

@@ -8540,7 +8540,10 @@
 \effects
 For the first overload, all reserved blocks are deallocated, and
 \tcode{capacity()} is reduced accordingly.
-For the second overload, \tcode{capacity()} is reduced to no less than \tcode{n}.
+For the second overload,
+if \tcode{n >= capacity()} is \tcode{true},
+there are no effects;
+otherwise, \tcode{capacity()} is reduced to no less than \tcode{n}.
 
 \pnum
 \complexity