docs(ngEventDirs): document priority of event directives

The general assumption is that if @priority is not defined, the priority is 0. BUT it's not
necessarily harmful to be explicit about this.

Closes angular#5852

Author: apolishch

src/ng/directive/ngEventDirs.js

@@ -9,6 +9,7 @@
  * an element is clicked.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngClick {@link guide/expression Expression} to evaluate upon
  * click. (Event object is available as `$event`)
  *
@@ -65,6 +66,7 @@ forEach(
  * The `ngDblclick` directive allows you to specify custom behavior on a dblclick event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngDblclick {@link guide/expression Expression} to evaluate upon
  * a dblclick. (The Event object is available as `$event`)
  *
@@ -88,6 +90,7 @@ forEach(
  * The ngMousedown directive allows you to specify custom behavior on mousedown event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngMousedown {@link guide/expression Expression} to evaluate upon
  * mousedown. (Event object is available as `$event`)
  *
@@ -111,6 +114,7 @@ forEach(
  * Specify custom behavior on mouseup event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngMouseup {@link guide/expression Expression} to evaluate upon
  * mouseup. (Event object is available as `$event`)
  *
@@ -133,6 +137,7 @@ forEach(
  * Specify custom behavior on mouseover event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngMouseover {@link guide/expression Expression} to evaluate upon
  * mouseover. (Event object is available as `$event`)
  *
@@ -156,6 +161,7 @@ forEach(
  * Specify custom behavior on mouseenter event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngMouseenter {@link guide/expression Expression} to evaluate upon
  * mouseenter. (Event object is available as `$event`)
  *
@@ -179,6 +185,7 @@ forEach(
  * Specify custom behavior on mouseleave event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngMouseleave {@link guide/expression Expression} to evaluate upon
  * mouseleave. (Event object is available as `$event`)
  *
@@ -202,6 +209,7 @@ forEach(
  * Specify custom behavior on mousemove event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngMousemove {@link guide/expression Expression} to evaluate upon
  * mousemove. (Event object is available as `$event`)
  *
@@ -225,6 +233,7 @@ forEach(
  * Specify custom behavior on keydown event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngKeydown {@link guide/expression Expression} to evaluate upon
  * keydown. (Event object is available as `$event` and can be interrogated for keyCode, altKey, etc.)
  *
@@ -246,6 +255,7 @@ forEach(
  * Specify custom behavior on keyup event.
  *
  * @element ANY
+ * @priority 0
  * @param {expression} ngKeyup {@link guide/expression Expression} to evaluate upon
  * keyup. (Event object is available as `$event` and can be interrogated for keyCode, altKey, etc.)
  *
@@ -292,6 +302,7 @@ forEach(
  * attribute**.
  *
  * @element form
+ * @priority 0
  * @param {expression} ngSubmit {@link guide/expression Expression} to eval. (Event object is available as `$event`)
  *
  * @example
@@ -341,6 +352,7 @@ forEach(
  * Specify custom behavior on focus event.
  *
  * @element window, input, select, textarea, a
+ * @priority 0
  * @param {expression} ngFocus {@link guide/expression Expression} to evaluate upon
  * focus. (Event object is available as `$event`)
  *
@@ -356,6 +368,7 @@ forEach(
  * Specify custom behavior on blur event.
  *
  * @element window, input, select, textarea, a
+ * @priority 0
  * @param {expression} ngBlur {@link guide/expression Expression} to evaluate upon
  * blur. (Event object is available as `$event`)
  *
@@ -371,6 +384,7 @@ forEach(
  * Specify custom behavior on copy event.
  *
  * @element window, input, select, textarea, a
+ * @priority 0
  * @param {expression} ngCopy {@link guide/expression Expression} to evaluate upon
  * copy. (Event object is available as `$event`)
  *
@@ -391,6 +405,7 @@ forEach(
  * Specify custom behavior on cut event.
  *
  * @element window, input, select, textarea, a
+ * @priority 0
  * @param {expression} ngCut {@link guide/expression Expression} to evaluate upon
  * cut. (Event object is available as `$event`)
  *
@@ -411,6 +426,7 @@ forEach(
  * Specify custom behavior on paste event.
  *
  * @element window, input, select, textarea, a
+ * @priority 0
  * @param {expression} ngPaste {@link guide/expression Expression} to evaluate upon
  * paste. (Event object is available as `$event`)
  *