mention updates in resttemplate documentation [SPR-11173]

[spring-projects-issues]

Brian Clozel opened SPR-11173 and commented

Mention both #new-in-3.2-webmvc-http-patch and #new-in-3.2-webmvc-generic-types-rest-template in #rest-client-access

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Affects: 4.0 RC2

This issue is a sub-task of #15775

Referenced from: commits ad1a681