add comments

src/ui/map.js

@@ -614,6 +614,11 @@ class Map extends Camera {
      * If the map's current zoom level is lower than the new minimum,
      * the map will zoom to the new minimum.
      *
+     * It is not always possible to zoom out and reach the set `minZoom`.
+     * Other factors such as map height may restrict zooming. For example,
+     * if the map is 512px tall it will not be possible to zoom below zoom 0
+     * no matter what the `minZoom` is set to.
+     *
      * @param {number | null | undefined} minZoom The minimum zoom level to set (-2 - 24).
      *   If `null` or `undefined` is provided, the function removes the current minimum zoom (i.e. sets it to -2).
      * @returns {Map} `this`