[io grant] Reword/expand IO::Path intro prose

Author: zoffixznet

doc/Type/IO/Path.pod6

@@ -7,23 +7,36 @@
 =for code :skip-test
 class IO::Path is Cool does IO { }
 
-Built-in class for file and directory paths.
-
-Conceptually, an C<IO::Path> object consists of a volume (think C<C:> on
-windows), a directory, and a basename.
-
-C<IO::Path> supports both purely textual operations, and operations that
-access the file system.
-
-The current working directory is available as an C<IO::Path> object in C<$*CWD>.
-
-The behavior of C<IO::Path> is dependent on the operating system it runs on;
-to get reproducible behavior across operating systems, you can use one of its
-subclasses instead: L<IO::Spec::Unix>, L<IO::Spec::Win32>,
-L<IO::Spec::Cygwin>, L<IO::Spec::QNX>.
+The workhorse of IO operations.
+
+Conceptually, an C<IO::Path> object consists of a volume, a directory, and a
+basename. It supports both purely textual operations, and operations that access
+the file system, e.g. to resolve a path, or to read all content of a file.
+
+At creation, each C<IO::Path> object is given information about the current
+working directory the path might be relative to using the C<$.CWD> attribute
+(defaults to L«C<$*CWD>|/language/variables#Dynamic_variables»), as well as
+what operating system semantics should be used for path manipulation using
+the special L«C<IO::Spec>|/type/IO::Spec» type given in the C<$.SPEC> attribute.
+
+The C<$.SPEC> defaults to the value of
+L«C<$*SPEC>|/language/variables#Dynamic_variables», which uses the object
+suitable for the operating system the code is currently running on. This is
+the default most code will be comfortable with.
+
+In certain situations, e.g. testing, you may wish to force C<$*SPEC> to use one
+of the specific SPEC modules: L«C<IO::Spec::Unix>|/type/IO::Spec::Unix»,
+L«C<IO::Spec::Win32>|/type/IO::Spec::Win32»,
+L«C<IO::Spec::Cygwin>|/type/IO::Spec::Cygwin», and
+L«C<IO::Spec::QNX>|/type/IO::Spec::QNX», or to create C<IO::Path> objects via
+shortcut subclasses L«C<IO::Path::Unix>|/type/IO::Path::Unix»,
+L«C<IO::Path::Win32>|/type/IO::Path::Win32»,
+L«C<IO::Path::Cygwin>|/type/IO::Path::Cygwin», and
+L«C<IO::Path::QNX>|/type/IO::Path::QNX» that pre-set the C<$.SPEC> attribute
+for you.
 
 The rest of this document silently assumes Unix semantics in its examples,
-unless when stated otherwise.
+unless stated otherwise.
 
 =head1 Methods