Disable HHAST by default

it executes $PROJECT/vendor/bin/hhast, so that's not a good idea.

doc/ale.txt

@@ -1214,6 +1214,7 @@ g:ale_linters                                                   *g:ale_linters*
   {
   \   'csh': ['shell'],
   \   'go': ['gofmt', 'golint', 'go vet'],
+  \   'hack': ['hack'],
   \   'help': [],
   \   'perl': ['perlcritic'],
   \   'python': ['flake8', 'mypy', 'pylint'],