[basics] add a note that splitting on a single space is not very robu…

…st. codyFendant++

src/basics.pod

@@ -151,6 +151,16 @@ strings C<'Beth', 'Ana', 'Charlie', 'Dave'>.  Finally, this list gets
 stored in the array C<@names>.  The C<@> sigil marks the declared variable as
 an C<Array>.  Arrays store ordered lists.
 
+=begin sidebar
+
+Splitting on a single blank is not very robust, and breaks the code when
+there are trailing spaces in a line, or more than one blank in a row. You will
+learn a more robust method for data extraction in the chapter about regexes.
+
+TODO: proper cross-link
+
+=end sidebar
+
 =begin programlisting
 
     my %matches;