Fix broken links (#1)

- Always use a relative markdown link so that we can jump even if we edit it in local env or read it in code hosting server.

Reviewed-on: https://gitea.com/gitea/docs/pulls/1

versioned_docs/version-1.22/installation/comparison.md

@@ -88,7 +88,7 @@ _Symbols used in table:_
 | Visual comparison of image changes          | ✓                                                   | ✘    | ✓         | ?         | ?         | ?         | ✘            | ✘            |
 
 - Gitea has builtin repository-level code search
-- Better code search support could be achieved by [using a repository indexer](administration/repo-indexer.md)
+- Better code search support could be achieved by [using a repository indexer](../administration/repo-indexer.md)
 
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