doc: use consistent event name parameter

Implementing the suggestion in
https://github.com/nodejs/node/issues/4554 this pull request renames
the parameter name in all the places that accept an event name as a parameter.

Previously, the parameter has been called `event` or `type`. Now as suggested
it is consistently called `eventName`.

PR-URL: https://github.com/nodejs/node/pull/5850
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

doc/api/events.markdown

@@ -201,7 +201,7 @@ added and `'removeListener'` when a listener is removed.
 
 ### Event: 'newListener'
 
-* `event` {String|Symbol} The event name
+* `eventName` {String|Symbol} The name of the event being listened for
 * `listener` {Function} The event handler function
 
 The `EventEmitter` instance will emit it's own `'newListener'` event *before*
@@ -237,16 +237,16 @@ myEmitter.emit('event');
 
 ### Event: 'removeListener'
 
-* `event` {String|Symbol} The event name
+* `eventName` {String|Symbol} The event name
 * `listener` {Function} The event handler function
 
 The `'removeListener'` event is emitted *after* a listener is removed.
 
-### EventEmitter.listenerCount(emitter, event)
+### EventEmitter.listenerCount(emitter, eventName)
 
     Stability: 0 - Deprecated: Use [`emitter.listenerCount()`][] instead.
 
-A class method that returns the number of listeners for the given `event`
+A class method that returns the number of listeners for the given `eventName`
 registered on the given `emitter`.
 
 ```js
@@ -284,16 +284,17 @@ emitter.once('event', () => {
 });
 ```
 
-### emitter.addListener(event, listener)
+### emitter.addListener(eventName, listener)
 
-Alias for `emitter.on(event, listener)`.
+Alias for `emitter.on(eventName, listener)`.
 
-### emitter.emit(event[, arg1][, arg2][, ...])
+### emitter.emit(eventName[, arg1][, arg2][, ...])
 
-Synchronously calls each of the listeners registered for `event`, in the order
-they were registered, passing the supplied arguments to each.
+Synchronously calls each of the listeners registered for the event named
+`eventName`, in the order they were registered, passing the supplied arguments
+to each.
 
-Returns `true` if event had listeners, `false` otherwise.
+Returns `true` if the event had listeners, `false` otherwise.
 
 ### emitter.eventNames()
 
@@ -319,15 +320,15 @@ Returns the current max listener value for the `EventEmitter` which is either
 set by [`emitter.setMaxListeners(n)`][] or defaults to
 [`EventEmitter.defaultMaxListeners`][].
 
-### emitter.listenerCount(event)
+### emitter.listenerCount(eventName)
 
-* `event` {Value} The type of event
+* `eventName` {Value} The name of the event being listened for
 
-Returns the number of listeners listening to the `event` type.
+Returns the number of listeners listening to the event named `eventName`.
 
-### emitter.listeners(event)
+### emitter.listeners(eventName)
 
-Returns a copy of the array of listeners for the specified `event`.
+Returns a copy of the array of listeners for the event named `eventName`.
 
 ```js
 server.on('connection', (stream) => {
@@ -337,12 +338,12 @@ console.log(util.inspect(server.listeners('connection')));
   // Prints: [ [Function] ]
 ```
 
-### emitter.on(event, listener)
+### emitter.on(eventName, listener)
 
 Adds the `listener` function to the end of the listeners array for the
-specified `event`. No checks are made to see if the `listener` has already
-been added. Multiple calls passing the same combination of `event` and
-`listener` will result in the `listener` being added, and called, multiple
+event named `eventName`. No checks are made to see if the `listener` has
+already been added. Multiple calls passing the same combination of `eventName`
+and `listener` will result in the `listener` being added, and called, multiple
 times.
 
 ```js
@@ -353,10 +354,11 @@ server.on('connection', (stream) => {
 
 Returns a reference to the `EventEmitter` so calls can be chained.
 
-### emitter.once(event, listener)
+### emitter.once(eventName, listener)
 
-Adds a **one time** `listener` function for the `event`. This listener is
-invoked only the next time `event` is triggered, after which it is removed.
+Adds a **one time** `listener` function for the event named `eventName`. This
+listener is invoked only the next time `eventName` is triggered, after which
+it is removed.
 
 ```js
 server.once('connection', (stream) => {
@@ -366,9 +368,9 @@ server.once('connection', (stream) => {
 
 Returns a reference to the `EventEmitter` so calls can be chained.
 
-### emitter.removeAllListeners([event])
+### emitter.removeAllListeners([eventName])
 
-Removes all listeners, or those of the specified `event`.
+Removes all listeners, or those of the specified `eventName`.
 
 Note that it is bad practice to remove listeners added elsewhere in the code,
 particularly when the `EventEmitter` instance was created by some other
@@ -376,10 +378,10 @@ component or module (e.g. sockets or file streams).
 
 Returns a reference to the `EventEmitter` so calls can be chained.
 
-### emitter.removeListener(event, listener)
+### emitter.removeListener(eventName, listener)
 
-Removes the specified `listener` from the listener array for the specified
-`event`.
+Removes the specified `listener` from the listener array for the event named
+`eventName`.
 
 ```js
 var callback = (stream) => {
@@ -392,8 +394,8 @@ server.removeListener('connection', callback);
 
 `removeListener` will remove, at most, one instance of a listener from the
 listener array. If any single listener has been added multiple times to the
-listener array for the specified `event`, then `removeListener` must be called
-multiple times to remove each instance.
+listener array for the specified `eventName`, then `removeListener` must be
+called multiple times to remove each instance.
 
 Note that once an event has been emitted, all listeners attached to it at the
 time of emitting will be called in order. This implies that any `removeListener()`