docs(guide/Directives): add info about scope types

docs/content/guide/directive.ngdoc

@@ -448,7 +448,58 @@ This is clearly not a great solution.
 
 What we want to be able to do is separate the scope inside a directive from the scope
 outside, and then map the outer scope to a directive's inner scope. We can do this by creating what
-we call an **isolate scope**. To do this, we can use a directive's `scope` option:
+we call an **isolate scope**. 
+
+To understand this concept we must first explore the directive's **scope** option:
+
+* #### `scope`
+ * **If set to `true`,** then a new scope will be created for this directive. If multiple directives on the
+ * same element request a new scope, only one new scope is created. The new scope rule does not
+ * apply for the root of the template since the root of the template always gets a new scope.
+ *
+ * **If set to `{}` (object hash),** then a new "isolate" scope is created. The 'isolate' scope differs from
+ * normal scope in that it does not prototypically inherit from the parent scope. This is useful
+ * when creating reusable components, which should not accidentally read or modify data in the
+ * parent scope.
+ *
+ * The 'isolate' scope takes an object hash which defines a set of local scope properties
+ * derived from the parent scope. These local properties are useful for aliasing values for
+ * templates. Locals definition is a hash of local scope property to its source:
+ *
+ * * `@` or `@attr` - bind a local scope property to the value of DOM attribute. The result is
+ *   always a string since DOM attributes are strings. If no `attr` name is specified  then the
+ *   attribute name is assumed to be the same as the local name.
+ *   Given `<widget my-attr="hello {{name}}">` and widget definition
+ *   of `scope: { localName:'@myAttr' }`, then widget scope property `localName` will reflect
+ *   the interpolated value of `hello {{name}}`. As the `name` attribute changes so will the
+ *   `localName` property on the widget scope. The `name` is read from the parent scope (not
+ *   component scope).
+ *
+ * * `=` or `=attr` - set up bi-directional binding between a local scope property and the
+ *   parent scope property of name defined via the value of the `attr` attribute. If no `attr`
+ *   name is specified then the attribute name is assumed to be the same as the local name.
+ *   Given `<widget my-attr="parentModel">` and widget definition of
+ *   `scope: { localModel:'=myAttr' }`, then widget scope property `localModel` will reflect the
+ *   value of `parentModel` on the parent scope. Any changes to `parentModel` will be reflected
+ *   in `localModel` and any changes in `localModel` will reflect in `parentModel`. If the parent
+ *   scope property doesn't exist, it will throw a NON_ASSIGNABLE_MODEL_EXPRESSION exception. You
+ *   can avoid this behavior using `=?` or `=?attr` in order to flag the property as optional. If
+ *   you want to shallow watch for changes (i.e. $watchCollection instead of $watch) you can use
+ *   `=*` or `=*attr` (`=*?` or `=*?attr` if the property is optional).
+ *
+ * * `&` or `&attr` - provides a way to execute an expression in the context of the parent scope.
+ *   If no `attr` name is specified then the attribute name is assumed to be the same as the
+ *   local name. Given `<widget my-attr="count = count + value">` and widget definition of
+ *   `scope: { localFn:'&myAttr' }`, then isolate scope property `localFn` will point to
+ *   a function wrapper for the `count = count + value` expression. Often it's desirable to
+ *   pass data from the isolated scope via an expression to the parent scope, this can be
+ *   done by passing a map of local variable names and values into the expression wrapper fn.
+ *   For example, if the expression is `increment(amount)` then we can specify the amount value
+ *   by calling the `localFn` as `localFn({amount: 22})`.
+ *
+ *
+
+Applying this back to our example, we can use a directive's `scope` option:
 
 <example module="docsIsolateScopeDirective">
   <file name="script.js">