Remove "nondet volatile" and "function pointer" pages from user guide

The content of nondet-volatile.md and restrict-function-pointer.md in
doc/architectural has already been moved to the goto-instrument man page.
Remove this also from architectural main page front-page.md

Author: Mark R. Tuttle

doc/architectural/front-page.md

@@ -67,8 +67,6 @@ you can access it <a href=
 
 * \subpage memory-analyzer
 * \subpage memory-bounds-checking
-* \subpage nondet-volatile
-* \subpage restricting-function-pointers
 * \subpage satabs
 
 ### For contributors:

doc/architectural/nondet-volatile.md

@@ -15,8 +15,6 @@ Other tips for using CBMC:
 
 * \ref memory-analyzer
 * \ref memory-bounds-checking
-* \ref nondet-volatile
-* \ref restricting-function-pointers
 * \ref satabs
 
 This CBMC user guide is a work in progress.