Update build directory expression

In subsection "Running regression tests with ctest", build directory was not wrapped by ``. To make
consistent expression with the rest of the document, it was changed from
build to `build/`.

Author: diffblue QA

doc/architectural/compilation-and-development.md

@@ -93,7 +93,7 @@ folders.
 If you have compiled using CMake then you can run the regression tests (and
 the unit tests) using CTest.
 
-Here are two example commands, to be run from the build directory:
+Here are two example commands, to be run from the `build/` directory:
 
     ctest -V -L CORE -R cpp
     ctest -V -L CORE -R cpp -E cbmc-cpp