Typo fixes in inc/ and next/

A typo that was missed because I did not look at that part of the file
was 'quidelines' instead of 'guidelines'. This has been fixed in inc/
and next/.

inc/rules.pending.hdr

@@ -13,7 +13,7 @@ Mastodon](https://fosstodon.org/@ioccc) feed as _sometimes_ the
 
 See our [FAQ about providing feedback](../faq.html#feedback) as well
 as our [FAQ about asking questions](../faq.html#question) about
-these quidelines.
+these guidelines.
 
 
 # The IOCCC is not yet open