Update side-nav.tmpl to properly parse event hashes

The regexp did not properly match a JSDoc3-Compliant `@event` name.

```
    /**
     * Snowball event.
     *
     * @event Hurl#snowball
     * @type {object}
     * @property {boolean} isPacked - Indicates whether the snowball is tightly packed.
     */
```
becomes  `Hurl#event:snowball` which parses as:

**Prior:** `Hurl#event:snowball.html`

1.     `Hurl#event:snowball`

**Fixed:**  `Hurl.html#event:snowball`

1.	`Hurl`
2.	`#event:snowball`
3.	`event`
4.	`snowball`

*Warning: No tests have been published, therefore, this could break something else.*