Update README.md

README.md

@@ -8,6 +8,19 @@ Forked from [HTTP Switchboard](https://github.com/gorhill/httpswitchboard).
 
 [Differences](https://github.com/gorhill/uMatrix/wiki/Changes-from-HTTP-Switchboard) with HTTP Switchboard.
 
+## Warnings
+
+#### Regarding broken sites
+
+µMatrix do not guarantee sites will work fine: it is for advanced users who can figure how to unbreak sites, because essentially µMatrix is a firewall which works in block-all/allow-exceptionally mode out of the box: it not unexpected sites will break.
+
+**So this means do not file issues to report broken sites when the sites are broken because µMatrix does its job as expected.** I will close any such issue without further comment.
+
+I expect there will be community driven efforts for users to help each others.
+
+µMatrix can be set to work in allow-all/block-exceptionally mode with a single click on the `all` cell in the global scope `*`, if you prefer to work this way. This will of course break less sites, but than you would lose all the benefit which comes with block-all/allow-exceptionally mode.
+
+
 ## License
 
 <a href="https://github.com/gorhill/umatrix/blob/master/LICENSE.txt">GPLv3</a>.