[COMMITTED] doc: document that $<..> accepts using substrings

[Jose E. Marchesi]

2023-11-02  Jose E. Marchesi  <jemarch@gnu.org>

        * doc/poke.texi (Files as IO Spaces): Document that $<...>
        supports specifying a non ambiguous non-empty substring.
---
 ChangeLog     |  5 +++++
 doc/poke.texi | 15 ++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 61054621..17ead859 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2023-11-02  Jose E. Marchesi  <jemarch@gnu.org>
+
+       * doc/poke.texi (Files as IO Spaces): Document that $<...>
+       supports specifying a non ambiguous non-empty substring.
+
 2023-11-01  Jose E. Marchesi  <jemarch@gnu.org>
 
        * libpoke/ios.h: Prototype for ios_get_handler.
diff --git a/doc/poke.texi b/doc/poke.texi
index c33de23c..01ed802a 100644
--- a/doc/poke.texi
+++ b/doc/poke.texi
@@ -1210,7 +1210,20 @@ The current IOS is now `./foo.o'.
 @end example
 
 @noindent
-Awesome.  Now we can focus on @file{foo.o}'s contents@dots{}
+Note that the @code{$<@var{name}>} construct in lenient in the sense
+that it will accept any non-empty sub string that identifies an
+existing IO space in an unambiguous way.  This is useful in order to
+avoid having to write annoying paths.  For example:
+
+@example
+(poke) .file /bin/ls
+(poke) .file /bin/cat
+(poke) .ios $<ls>
+The current IOS is now `/bin/ls'.
+@end example
+
+@noindent
+Auto completion also works.  Try it!
 
 @node Dumping File Contents
 @section Dumping File Contents
-- 
2.30.2