chore: import upstream snapshot with attribution

docs/functions/this.html

@@ -0,0 +1,18 @@
+<h5>THIS</h5>
+<br>
+<p>This namespace contains functions that are used with the current item in the context menu.</p>
+<br>
+<section id="syntax" class="my-5">
+	<h5>Syntax</h5>
+	<pre><code>
+this.type	// Returns the type of the current item [item = 0, menu = 1, separator = 2]
+this.checked	// Returns true if the current item is checked
+this.pos	// Returns the position of the current item in the context menu
+this.disabled	// Returns true if the current item is disabled
+this.sys	// Returns true if the current item is a system item
+this.title	// Returns the title of the current item
+this.id		// Returns the ID of the current item
+this.count	// Returns the number of items in the context menu
+this.length	// Returns the length of the current item's title
+</code></pre>
+</section>