Add functional notations for `dist`
Add functional notations for dist in parallel to equiv, namely (≡{n}≡), (≡{n}@{A}≡), (x ≡{n}≡.) and (.≡{n}≡ y).
Add functional notations for dist in parallel to equiv, namely (≡{n}≡), (≡{n}@{A}≡), (x ≡{n}≡.) and (.≡{n}≡ y).