Remove the documentation verification step

This step is now performed by GitHub Actions.

Author: ahoppen

utils/swift_build_support/swift_build_support/products/swiftsyntax.py

@@ -119,8 +119,6 @@ def build(self, host_target):
                 "verify-source-code",
                 ['--toolchain', self.install_toolchain_path(host_target)]
             )
-            if platform.system() == 'Darwin':
-                self.run_swift_syntax_dev_utils(host_target, "verify-documentation", [])
 
         self.run_swiftsyntax_build_script(target=host_target,
                                           command='build')