Fix broken link & update .lycheeignore

Author: thomas-zahner

.lycheeignore

@@ -1,13 +1,17 @@
-https://api.reacher.email/v0/check_email
 file:///home/user/website/
 ^https://www/$
 ^https://web/$
-# Errors with "Too Many Requests"
-https://www.nongnu.org/atool
+
+# URL is used with POST
+https://api.reacher.email/v0/check_email
 
 # 404 page is directly in dist/404.html but we've remapped it to an invalid path
 dist/404/index.html$
 
 # Code examples in base-url.mdx which don't exist
 /docs/about.php$
 /docs/recipes/guide.php$
+
+# Websites with aggressive rate limiting / bot detection
+https://www.nongnu.org/atool
+https://builtwith.com/

src/content/docs/guides/getting-started.mdx

@@ -210,7 +210,7 @@ In this command, we ignore the case when globbing, so it matches
 
 By preprocessing files it is possible to do link checking on
 files which aren't officially supported by lychee.
-See [file preprocessing](preprocessing).
+See [file preprocessing](/guides/preprocessing).
 
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