Add FUQ about fish as the default shell

fuqs/index.html

@@ -61,6 +61,13 @@
                 Please report it in the <a href="https://git.exozy.me/exozyme/Issues">Issues repository</a>.
             </p>
             <br>
+            <p>
+                <b>The command line is behaving weirdly, commands I copied from the internet don't work, editing my <i>~/.bashrc</i> isn't working, and I can't change my shell!</b>
+            </p>
+            <p>
+                These issues are all consequences of using <a href="https://fishshell.com/">Fish</a> as the default shell for new users instead of the typical Bash. Although Fish is much easier to use than Bash, it's also not very compatible with Bash commands. You probably shouldn't blindly copy commands from the internet, but if you do, run <i>bash</i> first to get a Bash shell before pasting them in. If you want to run commands when starting the shell as with a <i>~/.bashrc</i>, see <a href="https://unix.stackexchange.com/a/211529">this Stack Exchange post</a>. And if you get tired of fish, you can always change you shell by asking about it on Matrix.
+            </p>
+            <br>
             <p>
                 <b>Help! I forgot my password to <i>X</i> and the reset password thing doesn't work!</b>
             </p>