Change to manifest v3, documentation updates

README.org

@@ -3,13 +3,29 @@
 #+OPTIONS: toc:nil
 *yt-share-cleaner* is an extension that removes tracking from YouTube share links.
 
-[[https://addons.mozilla.org/firefox/addon/yt-share-cleaner/][https://blog.mozilla.org/addons/files/2015/11/get-the-addon.png]] [[https://www.firefox.com/download][https://developer.chrome.com/static/docs/webstore/branding/image/UV4C4ybeBTsZt43U4xis.png]]
+[[https://addons.mozilla.org/firefox/addon/yt-share-cleaner/][https://blog.mozilla.org/addons/files/2015/11/get-the-addon.png]]
+[[https://www.firefox.com/download][https://developer.chrome.com/static/docs/webstore/branding/image/UV4C4ybeBTsZt43U4xis.png]]
 
-When using the `Share` button -> `Copy` button to copy the share link, YouTube
+* Purpose
+When using the ~Share~ button -> ~Copy~ button to copy the share link, YouTube
 adds a tracking portion to the URL.
 
-To deal with this annoyance, yt-share-cleaner:
-1. runs whenever the mouse is clicked
-2. reads the contents of the clipboard
-3. if the clipboard has a YouTube share link, remove the tracking portion and
-   write the new URL to the clipboard
+
+* Installation
+** Firefox
+Install yt-share-cleaner using the AMO link above.
+
+** Chrome, Chromium-based browsers
+These are not supported, but the extension should work on them as well.
+
+Not available on the Chrome Web Store. I am not inclined to pay Google's
+registration fee. See your browser's documentation on installing 3rd-party
+extensions. 
+
+
+
+* Usage
+1. click on the ~Copy~ button
+2. yt-share-cleaner reads the clipboard; if the content is a YouTube share link,
+   the tracking parameter is removed
+3. yt-share-cleaner writes the cleaned link to the clipboard