Replace command line Step 5 Install Homebrew

  replace brew install "qt5 --with-qtwebkit" with "install qt5" otherwise it will not work

doc/building.rst

@@ -47,7 +47,7 @@ To set up your build environment for development using HomeBrew_:
 
 5. Install a Qt5 version with qtwebkit support::
 
-    brew install qt5 --with-qtwebkit
+    brew install qt5
 
 6. Install any missing dependencies::