docs(autocomplete): add autocomplete docs (angular#2840)

src/lib/autocomplete/OVERVIEW.md

@@ -0,0 +1,150 @@
+
+The autocomplete is a normal text input enhanced by a panel of suggested options. You can read more about 
+autocompletes in the [Material Design spec](https://material.io/guidelines/components/text-fields.html#text-fields-auto-complete-text-field).
+
+### Simple autocomplete
+
+Start by adding a regular `mdInput` to the page. Let's assume you're using the `formControl` directive from the 
+`@angular/forms` module to track the value of the input.
+
+*my-comp.html*
+```html
+<md-input-container>
+   <input type="text" mdInput [formControl]="myControl">
+</md-input-container>
+```
+
+Next, create the autocomplete panel and the options displayed inside it. Each option should be defined by an 
+`md-option` tag. Set each option's value property to whatever you'd like the value of the text input to be 
+upon that option's selection.
+
+*my-comp.html*
+```html
+<md-autocomplete>
+   <md-option *ngFor="let option of options" [value]="option">
+      {{ option }}
+   </md-option>
+</md-autocomplete>
+```
+
+Now we'll need to link the text input to its panel. We can do this by exporting the autocomplete panel instance into a 
+local template variable (here we called it "auto"), and binding that variable to the input's `mdAutocomplete` property.
+
+*my-comp.html*
+```html
+<md-input-container>
+   <input type="text" mdInput [formControl]="myControl" [mdAutocomplete]="auto">
+</md-input-container>
+
+<md-autocomplete #auto="mdAutocomplete">
+   <md-option *ngFor="let option of options" [value]="option">
+      {{ option }}
+   </md-option>
+</md-autocomplete>
+```
+
+### Adding a custom filter
+
+At this point, the autocomplete panel should be toggleable on focus and options should be selectable. But if we want 
+our options to filter when we type, we need to add a custom filter. 
+
+You can filter the options in any way you want based on the text input. Here we will do a simple string test on the 
+input value to see if it matches the option value. We already have access to the built-in `valueChanges` observable on 
+the `FormControl`, so we can simply map the text input's values to the suggested options by passing them through this 
+filter. The resulting observable (`filteredOptions`) can be added to the template in place of the `options` property 
+using the `async` pipe.
+
+Below we are also priming our value change stream with `null` so that the options are filtered by that value on init 
+(before there are any value changes).
+
+*my-comp.ts*
+```ts
+class MyComp {
+   myControl = new FormControl();
+   options = [
+    'One',
+    'Two',
+    'Three'
+   ];
+   filteredOptions: Observable<string[]>;
+
+   ngOnInit() {
+      this.filteredOptions = this.myControl.valueChanges
+         .startWith(null)
+         .map(val => val ? this.filter(val) : this.options.slice());
+   }
+
+   filter(val: string): string[] {
+      return this.options.filter(option => new RegExp(val, 'gi').test(option)); 
+   }
+}
+```
+
+*my-comp.html*
+```html
+<md-input-container>
+   <input type="text" mdInput [formControl]="myControl" [mdAutocomplete]="auto">
+</md-input-container>
+
+<md-autocomplete #auto="mdAutocomplete">
+   <md-option *ngFor="let option of filteredOptions | async" [value]="option">
+      {{ option }}
+   </md-option>
+</md-autocomplete>
+```
+
+### Setting separate control and display values
+
+If you want the option's control value (what is saved in the form) to be different than the option's display value 
+(what is displayed in the actual text field), you'll need to set the `displayWith` property on your autocomplete 
+element. A common use case for this might be if you want to save your data as an object, but display just one of 
+the option's string properties.
+
+To make this work, create a function on your component class that maps the control value to the desired display value. 
+Then bind it to the autocomplete's `displayWith` property. 
+
+```html
+<md-input-container>
+   <input type="text" mdInput [formControl]="myControl" [mdAutocomplete]="auto">
+</md-input-container>
+
+<md-autocomplete #auto="mdAutocomplete" [displayWith]="displayFn">
+   <md-option *ngFor="let option of filteredOptions | async" [value]="option">
+      {{ option }}
+   </md-option>
+</md-autocomplete>
+```
+
+*my-comp.ts*
+```ts
+class MyComp {
+   myControl = new FormControl();
+   options = [
+     new User('Mary'),
+     new User('Shelley'),
+     new User('Igor')
+   ];
+   filteredOptions: Observable<User[]>;
+
+   ngOnInit() { 
+      this.filteredOptions = this.myControl.valueChanges
+         .startWith(null)
+         .map(user => user && typeof user === 'object' ? user.name : user)
+         .map(name => name ? this.filter(name) : this.options.slice());
+   }
+
+   filter(name: string): User[] {
+      return this.options.filter(option => new RegExp(name, 'gi').test(option)); 
+   }
+
+   displayFn(user: User): string {
+      return user ? user.name : user;
+   }
+}
+```
+
+
+#### Keyboard interaction:
+- <kbd>DOWN_ARROW</kbd>: Next option becomes active.
+- <kbd>UP_ARROW</kbd>: Previous option becomes active.
+- <kbd>ENTER</kbd>: Select currently active item.

src/lib/autocomplete/README.md

@@ -1,5 +1 @@
-
-## Not yet implemented!
-
-The autocomplete is not yet implemented. This is only a scaffold to make
-subsequent PRs easier to read. Please do not try to use yet :)
+See documentation on [material.angular.io](https://material.angular.io/).