multiple pages: standardize domain examples (#3010)

This change standardizes URL examples in tldr-pages
to use the canonical example.com domain.

Pages changed: `dig`, `drill`, `irssi`, `salt`, and `socat`.

pages/common/socat.md

@@ -8,8 +8,8 @@
 
 - Create a connection to a host and port, transfer data in STDIO to connected host:
 
-`socat - TCP4:www.domain.com:80`
+`socat - TCP4:www.example.com:80`
 
 - Forward incoming data of a local port to another host and port:
 
-`socat TCP-LISTEN:80,fork TCP4:www.domain.com:80`
+`socat TCP-LISTEN:80,fork TCP4:www.example.com:80`