add note about imperfect checks

index.html

@@ -38,6 +38,8 @@
 
 		<p>It's as simple as the image at the top makes it look! Just highlight the URL of an instance you want to silence or suspend, and select the new context option. It does a little bit of simple sanitizing and validation to make sure you highlighted what you wanted to highlight. Then, it checks to see if the instance is already limited. Finally, it opens a new tab to your instance's "New Domain Block" form.</p>
 
+		<p>The checks to ensure that the highlighted text is a domain and that it's not already limited on the instance are imperfect. For example, if the instance "domain.tld" is blocked, the latter check will give a false positive on "mydomain.tld". For this reason, the checks can be overridden manually.</p>
+
 		<h3>What is a userscript?</h3>
 
 		<p>A userscript is sort of like a browser extension, but smaller! Just a little bit of Javascript code that gets run on certain pages to enhance the experience.</p>