Add @moduledoc false and @doc false as snippets

[axelson]

I fairly often use @moduledoc false and @doc false but previously there was no autocompletion for them.

Add @moduledoc false with a "lower" priority
Add """""" to the snippet name to indicate that the snippet will insert a heredoc

Before:

After:

[axelson]

Test failure is unrelated so I'm going to merge this.