Fix a bad typo

Caught an egregious typing error from my own earlier work.

Author: Jay Bryant

spring-session-docs/src/docs/asciidoc/index.adoc

@@ -289,7 +289,7 @@ Any method that returns an `HttpSession` is overridden.
 All other methods are implemented by `HttpServletRequestWrapper` and delegate to the original `HttpServletRequest` implementation.
 
 We replace the `HttpServletRequest` implementation by using a servlet `Filter` called `SessionRepositoryFilter`.
-The pseudocode belows:
+The following pseudocode shows how it works:
 
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 [source, java]