npm: don't package unnecessary files

When CI builds the npm package, it includes a bunch of files which don't
belong in the npm package such as the Vim plugin and shell completion
scripts. Remove these files from the npm package because no one will use
them anyway.

Author: strager

dist/npm/.npmignore

@@ -1 +1,24 @@
-# Empty file.
+# Copyright (C) 2020  Matthew "strager" Glazar
+# See end of file for extended copyright information.
+
+/darwin-*/share/
+/linux-*/share/
+/win32-*/share/
+
+# quick-lint-js finds bugs in JavaScript programs.
+# Copyright (C) 2020  Matthew "strager" Glazar
+#
+# This file is part of quick-lint-js.
+#
+# quick-lint-js is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# quick-lint-js is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with quick-lint-js.  If not, see <https://www.gnu.org/licenses/>.