address comments

Author: tinayuangao

src/lib/chips/chips.md

@@ -40,5 +40,5 @@ use a neutral background color based on the current theme (light or dark). This
 `'primary'`, `'accent'`, or `'warn'`.
 
 ### Accessibility
-Chips has `role="option"` while chip list has `role="listbox"`. The chip input should have a
+Chips have role="option", while the chip list has `role="listbox"`. The chip input should have a
 placeholder or be given a meaningful label via `aria-label` or `aria-labelledby`.

src/lib/dialog/dialog.md

@@ -128,5 +128,8 @@ export class AppModule() {}
 ```
 
 ### Accessibility
-The dialog has `role="dialog". The dialog will focus on the first tabbable element when opened,
+The dialog has `role="dialog", and dialog role can be overwritten to `alertdialog` in the
+appropriate context.
+
+The dialog will focus on the first tabbable element when opened,
 and restore focus to the element that was focused before the dialog opened when closed.

src/lib/expansion/expansion.md

@@ -103,5 +103,5 @@ panel can be expanded at a given time:
 The expansion panel header has `role="button"`. The expansion panel header has attribute
 `aria-controls` with the expansion panel's id as value.
 
-Users can use keyboard to activate the expansion panel header to switch between expanded state
+Users can use the keyboard to activate the expansion panel header to switch between expanded state
 and collapsed state.

src/lib/input/input.md

@@ -153,3 +153,10 @@ Here are the available global options:
 
 ### Accessibility
 The `mdInput` directive works with native `<input>` to provide an accessible experience.
+
+If a placeholder attributed is added to the input, or a `md-placeholder` element is added
+in the form field, the placeholder text will automatically be used as the label for the input.
+If there's no placeholder specified, `aria-label`, `aria-labelledby` or `<label for=...>` should be
+added.
+
+Any `md-error` and `md-hint` are automatically added to the input's `aria-describedby`.

src/lib/select/select.md

@@ -98,5 +98,3 @@ The select component without text or label should be given a meaningful label vi
 `aria-label` or `aria-labelledby`.
 
 The select component has `role="listbox"` and options inside select has `role="option"`.
-Autocomplete trigger sets `aria-owns` to the autocomplete's id, and sets `aria-activedescendant` to
-the active option's id.

src/lib/sort/sort.md

@@ -35,4 +35,4 @@ by default it will use the id of the column.
 <!-- example(table-sorting) -->
 
 ### Accessibility
-The `aria-label` for sort button can be set in `MdSortHeaderIntl`.
+The `aria-label` for the sort button can be set in `MdSortHeaderIntl`.

src/lib/tabs/tabs.md

@@ -81,5 +81,5 @@ the `active` property to determine which tab is currently active. The correspond
 `<router-outlet>` can be placed anywhere in the view.
 
 ### Accessibility
-`MdTanNav`s without text or labels should be given a meaningful label via `aria-label` or
+`MdTabNav`s without text or labels should be given a meaningful label via `aria-label` or
 `aria-labelledby`.