Normalise the help intro pages for each extension.

Specific content is still to come.

common/locale/en-US/intro.xml

@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<?xml-stylesheet type="text/xsl" href="chrome://dactyl/content/help.xsl"?>
+
+<!DOCTYPE document SYSTEM "chrome://dactyl/content/dactyl.dtd">
+
+<document
+    name="intro"
+    title="&dactyl.appName; Introduction"
+    xmlns="&xmlns.dactyl;"
+    xmlns:html="&xmlns.html;">
+
+<html:div style="text-align: center; clear: right; margin-bottom: -2.2em; padding-right: 4em;"><logo/></html:div>
+
+<h1 tag="intro">Introduction</h1>
+
+<p tag="intro-text"></p>
+
+<p tag="first-run">
+    If this is your first time running &dactyl.appName;, you may need some
+    time to adjust to the standard interface, which hides the menu,
+    navigation, and tool bars by default. If you find it uncomfortable to work
+    without them, you can re-enable them by typing
+</p>
+<set opt="guioptions" op="+="><str delim="">mT</str><k name="Return"/></set>
+<p>
+    If you have trouble remembering commands or keyboard shortcuts, you can
+    bring up this help page at any time by typing <ex>:help</ex> or
+    <k name="F1"/>. If you find that you don't like &dactyl.appName; at all,
+    you can disable it by typing <ex>:extdisable <str delim="">&dactyl.appName;</str></ex> or
+    delete it entirely by typing <ex>:extdelete <str delim="">&dactyl.appName;</str></ex>
+</p>
+
+<h2 tag="overview">Help topics</h2>
+
+<ol tag="topics-list"></ol>
+
+<p>
+    You can also jump directly to the help of a specific command,
+    key mapping, or topic via the <ex>:help</ex> command.
+</p>
+
+<example><ex>:help :help</ex></example>
+
+<h2 tag="features">Features</h2>
+
+<ul tag="features-list"></ul>
+
+<h2 tag="contact">Contact</h2>
+
+<p>
+    Please send comments, questions, or patches to the
+    <link topic="&dactyl.list.href;">mailing list</link>,
+    where we will do our best to answer any inquiries. You can also
+    check the
+    <link topic="http://code.google.com/p/dactyl/wiki">wiki</link> or
+    <link topic="&dactyl.faq;">FAQ</link>.
+    Issue reports can be entered in the
+    <link topic="&dactyl.issues;">issue tracker</link>.
+</p>
+
+</document>
+
+<!-- vim:se sts=4 sw=4 et: -->