Precise documentation of Tramp ad-hoc proxies

* doc/misc/tramp.texi (Ad-hoc multi-hops): Remove superfluous
first entry about %h and %u.  Describe, how to remove ad-hoc proxy
definitions.
(Cleanup remote connections): Mention, that also ad-hoc proxy
definitions are removed.

* etc/NEWS: Mention default host names in Tramp ad-hoc proxies.

doc/misc/tramp.texi

@@ -2778,13 +2778,14 @@ proxy @samp{bird@@bastion} to a remote file on @samp{you@@remotehost}:
 
 Each involved method must be an inline method (@pxref{Inline methods}).
 
-Proxies can take patterns @code{%h} or @code{%u}.
-
 @value{tramp} adds the ad-hoc definitions on the fly to
-@code{tramp-default-proxies-alist} and is available for re-use
-during that Emacs session.  Subsequent @value{tramp} connections to
-the same remote host can then use the shortcut form:
-@samp{@trampfn{ssh,you@@remotehost,/path}}.
+@code{tramp-default-proxies-alist} and is available for re-use during
+that Emacs session.  Subsequent @value{tramp} connections to the same
+remote host can then use the shortcut form:
+@samp{@trampfn{ssh,you@@remotehost,/path}}.  Ad-hoc definitions are
+removed from @code{tramp-default-proxies-alist} via the command
+@kbd{M-x tramp-cleanup-all-connections @key{RET}} (@pxref{Cleanup
+remote connections}).
 
 @defopt tramp-save-ad-hoc-proxies
 For ad-hoc definitions to be saved automatically in
@@ -3175,13 +3176,15 @@ as in @code{tramp-cleanup-connection}.
 
 @deffn Command tramp-cleanup-all-connections
 Flushes all active remote connection objects, the same as in
-@code{tramp-cleanup-connection}.
+@code{tramp-cleanup-connection}.  This command removes also ad-hoc
+proxy definitions (@pxref{Ad-hoc multi-hops}).
+
 @end deffn
 
 @deffn Command tramp-cleanup-all-buffers
 Just as for @code{tramp-cleanup-all-connections}, all remote
-connections are cleaned up in addition to killing buffers related to
-that remote connection.
+connections and ad-hoc proxy definition are cleaned up in addition to
+killing buffers related to that remote connection.
 @end deffn
 
 

etc/NEWS

@@ -910,7 +910,8 @@ Tramp for some look-alike remote file names.
 
 +++
 *** For some connection methods, like "su" or "sudo", the host name in
-ad-hoc multi-hop file names must match the previous hop.
+ad-hoc multi-hop file names must match the previous hop.  Default host
+names are adjusted to the host name from the previous hop.
 
 +++
 *** For the connection methods "sudo" and "doas" there exists a