Add vim modeline at end of every file without one

The settings in the modeline do the following:

* Highlight this file as Perl6
* Expand tabs into 4 spaces

This is helpful for vim users for highlighting an atypical file format
and creates formatting consistency with regards to tabs and spacing.

Author: jstuder-gh

doc/404.pod6

@@ -12,3 +12,5 @@
 </p>
 
 =end Html
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/HomePage.pod6

@@ -59,3 +59,5 @@ Documentation for the different but related <a href="https://www.perl.org/">Perl
 can be found on the <a href="http://perldoc.perl.org/">Perl 5 documentation website</a>.
 </p>
 =end Html
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/5to6-nutshell.pod6

@@ -1755,4 +1755,4 @@ be better than losing the information about a real need.
 
 =end comments
 
-# vim: expandtab shiftwidth=4 ft=perl6
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/5to6-perlfunc.pod6

@@ -1878,3 +1878,5 @@ This synonym for C<tr///> is gone. For functionality, see the entry for
 C<tr///>.
 
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/5to6-perlop.pod6

@@ -345,3 +345,5 @@ boolean or is C<?|>.
 Left shift and right shift are C<< +< >> and C<< +> >>.
 
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/5to6-perlsyn.pod6

@@ -184,3 +184,5 @@ perl6, you may need to specify the location of C<Pod::To::Text>.)
 Details on Perl 6 style pod is at L<https://design.perl6.org/S26.html>.
 
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/5to6-perlvar.pod6

@@ -543,3 +543,5 @@ It should go without saying that, as these have been removed from Perl 5
 already, there should be no need to tell you how to use them in Perl 6.
 
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/about.pod6

@@ -148,3 +148,5 @@ renders like this
 Notice that text after a pipe ('|') has no formatting. Also note that B<V< C<> >>
 preserves spaces and treats text as verbatim.
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/classtut.pod6

@@ -682,3 +682,5 @@ bunch of bytes needs to know the attributes of that object, which it can
 find out via introspection.
 
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/community.pod6

@@ -16,3 +16,5 @@ There is a large presence on the C<#perl6> channel on C<freenode.net>,
 who are happy to provide support and answer questions.
 
 =end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6