updated home page to make it clear what the archive icon is

src/pages/index.mdx

@@ -26,6 +26,10 @@ archives to help ensure that information isn't lost.
   Navigation to the content on the Transgender Resource Library can be found on the left for
 desktop users and in the top right corner for mobile users.
 
+&emsp; The <img style="display:inline; vertical-align:bottom; max-width:1.5rem;" src="../icons/archive.svg" alt="archive" />
+icon can be clicked to view an archived version of the page. This usually links to the internet
+archive unless the page is not available there, in which case a mirror of it will be hosted here.
+
 &nbsp;
 
 <HeartRow hearts={["../hearts/transgender_heart.png",