[io grant] Document :completely arg to IO::Path.resolve

Rakudo impl: rakudo/rakudo@6a8d63d1b6
Tests: Raku/roast@a809f0f1f5

Author: zoffixznet

doc/Type/IO/Path.pod6

@@ -308,17 +308,22 @@ needed and returns the result as a new C<IO::Path>.
 
 =head2 method resolve
 
-    method resolve(IO::Path:D: --> IO::Path)
+    method resolve(IO::Path:D: :$completely --> IO::Path)
 
 Returns a new C<IO::Path> object with all symbolic links and references to the
-parent directory (C<..>) resolved.  This means that the filesystem is examined
+parent directory (C<..>) resolved. This means that the filesystem is examined
 for each directory in the path, and any symlinks found are followed.
 
     # bar is a symlink pointing to "/baz"
     my $io = "foo/./bar/..".IO.resolve;      # now "/" (the parent of "/baz")
 
-NOTE: Currently (May 2016) this method doesn't work correctly on all platforms,
-e.g. Windows, since it assumes POSIX semantics.
+If C<$completely>, which defaults to C<False>, is set to a true value, the
+method will L«C<fail>|/routine/fail» if it cannot completely resolve the path,
+otherwise, it will resolve as much as possible, and will merely perform
+L«C<cleanup>|/routine/cleanup» of the rest of the path.
+
+NOTE: Currently (April 2017) this method doesn't work correctly on all
+platforms, e.g. Windows, since it assumes POSIX semantics.
 
 =head2 routine dir