Fix link to chapter introduction

[dancer1325]

Context

In https://docs.spring.io/spring-framework/reference/core/beans/context-introduction.html, you can read as first statement

As discussed in the chapter introduction, the org.springframework.beans.factory package provides basic functionality for managing and manipulating beans, including in a programmatic way

which redirects to https://docs.spring.io/spring-framework/reference/web/webmvc-view/mvc-xslt.html#mvc-view-xslt-beandefs, that

• it's not a chapter introduction section
• there is NO reference about "beans.factory" package

Description

• Switch linked page to the more accurated one (IMHO), https://docs.spring.io/spring-framework/reference/core/beans/basics.html

How to review?

• Check that the suggested refered page makes more sense than previous one

[bclozel]

Thanks for your contribution @dancer1325 . It looks like our migration process to Antora broke this link as it was initially correct.