docs(migration): clarify non-numeric matching

Closes angular#12350

Author: petebacondarwin

docs/content/guide/migration.ngdoc

@@ -194,8 +194,9 @@ in which the properties were defined.
 
 Due to [7fda214c](https://github.com/angular/angular.js/commit/7fda214c4f65a6a06b25cf5d5aff013a364e9cef),
 the `select` directive will now use strict comparison of the `ngModel` scope value against `option`
-values to determine which option is selected. This means `Number` scope values will not be matched
-against numeric option strings.
+values to determine which option is selected. This means non-string scope values (such as `Number` or `Boolean`)
+will not be matched against equivalent option strings (such as the strings `"123"`, `"true"` or `"false"`).
+
 In Angular 1.3.x, setting `scope.x = 200` would select the option with the value 200 in the following `select`:
 
 ```
@@ -206,7 +207,8 @@ In Angular 1.3.x, setting `scope.x = 200` would select the option with the value
 ```
 
 In Angular 1.4.x, the 'unknown option' will be selected.
-To remedy this, you can simply initialize the model as a string: `scope.x = '200'`, or if you want to
+
+To remedy this, you can initialize the model as a string: `scope.x = '200'`, or if you want to
 keep the model as a `Number`, you can do the conversion via `$formatters` and `$parsers` on `ngModel`:
 
 ```js