Use (banner) instead of a fixed "Welcome to Racket" in the More tutorial

and in the guide.

Also, add a tag to the readline "License Issues" to be able to link to
it from the xrepl docs.

collects/readline/readline.scrbl

@@ -241,7 +241,7 @@ from @racketmodname[ffi/unsafe], determines the type of value supplied
 to the @racket[proc].}
 
 
-@section{License Issues}
+@section[#:tag "readline-license"]{License Issues}
 
 GNU's @|readline| library is covered by the GPL, and that applies to
 code that links with it.  Racket is licensed with the LGPL, so the

collects/scribblings/guide/running.scrbl

@@ -34,7 +34,7 @@ confguration options, like @Flag{j}), then it starts a @tech{REPL}
 with a @litchar{> } prompt:
 
 @verbatim[#:indent 2]{
-  Welcome to Racket
+  @(regexp-replace #rx"\n+$" (banner) "")
   > 
 }
 

collects/scribblings/more/more.scrbl

@@ -75,7 +75,7 @@ start @exec{racket} with no command-line arguments:
 
 @verbatim[#:indent 2]{
   $ racket
-  Welcome to Racket
+  @(regexp-replace #rx"\n+$" (banner) "")
   > 
 }