Add some more extensions from Lua 5.2/5.3.

Contributed by François Perrad.

doc/extensions.html

@@ -303,6 +303,7 @@ enabled:
 <li><tt>os.exit(status|true|false [,close])</tt>.</li>
 <li><tt>package.searchpath(name, path [, sep [, rep]])</tt>.</li>
 <li><tt>package.loadlib(name, "*")</tt>.</li>
+<li><tt>package.searchers</tt>.</li>
 <li><tt>debug.getinfo()</tt> returns <tt>nparams</tt> and <tt>isvararg</tt>
 for option <tt>"u"</tt>.</li>
 <li><tt>debug.getlocal()</tt> accepts function instead of level.</li>
@@ -350,6 +351,9 @@ LuaJIT supports some extensions from Lua&nbsp;5.3:
 <ul>
 <li>Unicode escape <tt>'\u{XX...}'</tt> embeds the UTF-8 encoding in string literals.</li>
 <li>The argument table <tt>arg</tt> can be read (and modified) by <tt>LUA_INIT</tt> and <tt>-e</tt> chunks.</li>
+<li><tt>io.read()</tt> and <tt>file:read()</tt> accept formats with or without a leading <tt>*</tt>.</li>
+<li><tt>table.move(a1, f, e, t [,a2])</tt>.</li>
+<li><tt>coroutine.isyieldable()</tt>.</li>
 </ul>
 
 <h2 id="exceptions">C++ Exception Interoperability</h2>