Add advice about +r to webchat.md (#157)

I apparently forgot to mention this in the guide.
Also tweak wording about lost users.

Author: meldra

content/_guides/webchat.md

@@ -39,11 +39,10 @@ in some situations.
 Embedding or linking to a webchat on your project or group's website can
 encourage people to engage with your community and help it grow.
 
-However if you just link directly to our webchat, people may not know how
-to find your channel and become lost on the network. Often people
-show up in the main `#libera` channel asking specific questions about your
-project. It can be discouraging to them when nobody there knows what
-they are talking about!
+However, if you just link directly to our webchat, people may not know how to
+find your channel and become lost on the network. Often people show up in the
+main `#libera` channel asking specific questions about a project. It can be
+discouraging to them when nobody there knows what they are talking about!
 
 Crafting a URL that pre-fills the webchat form with your channel can prevent
 your users getting lost on the way.
@@ -52,6 +51,12 @@ Use the instructions below, but replace `#libera` with your channel instead.
 If you wish for your new visitors to have a different pre-filled nick then
 you can replace `Guest` in the URLs with the prefix of your choice.
 
+Keep in mind that webchat visitors frequently don’t have accounts. Often it's
+their first time on IRC. If your channel has set the `+r` mode, then they will
+not be able to join. You may need to reconsider the use of `+r`. While it is a
+good idea to [advise users to register](/guides/registration), if this is
+required it will discourage some users.
+
 ### Kiwiirc
 
 To make a link for your users to click on that pre-fills your channel, you