more typo fix: consecutive-word duplications

Following previously finding, I then used `rg` to find other similar
typos, with false positives manually excluded, using the following
command:

    rg -t asciidoc -Pp '\b(\w+)\s+\1\b'

Author: ryenus

docs/manual/src/docs/asciidoc/_includes/about/getting-spring-security.adoc

@@ -195,7 +195,7 @@ If you use a milestone or release candidate version, you need to ensure that you
 [[getting-gradle]]
 == Gradle
 
-As most open source projects, Spring Security deploys its dependencies as Maven artifacts, which allows for for first-class Gradle support.
+As most open source projects, Spring Security deploys its dependencies as Maven artifacts, which allows for first-class Gradle support.
 The following topics provide detail on how to consume Spring Security when using Gradle.
 
 [[getting-gradle-boot]]

docs/manual/src/docs/asciidoc/_includes/reactive/exploits/headers.adoc

@@ -7,7 +7,7 @@ This section is dedicated to WebFlux based support for Security HTTP Response He
 [[webflux-headers-default]]
 == Default Security Headers
 
-Spring Security provides a <<headers-default,default set set of Security HTTP Response Headers>> to provide secure defaults.
+Spring Security provides a <<headers-default,default set of Security HTTP Response Headers>> to provide secure defaults.
 While each of these headers are considered best practice, it should be noted that not all clients utilize the headers, so additional testing is encouraged.
 
 You can customize specific headers.

docs/manual/src/docs/asciidoc/_includes/servlet/exploits/headers.adoc

@@ -7,7 +7,7 @@ This section is dedicated to servlet based support for Security HTTP Response He
 [[servlet-headers-default]]
 == Default Security Headers
 
-Spring Security provides a <<headers-default,default set set of Security HTTP Response Headers>> to provide secure defaults.
+Spring Security provides a <<headers-default,default set of Security HTTP Response Headers>> to provide secure defaults.
 While each of these headers are considered best practice, it should be noted that not all clients utilize the headers, so additional testing is encouraged.
 
 You can customize specific headers.

docs/manual/src/docs/asciidoc/_includes/servlet/saml2/saml2-login.adoc

@@ -226,7 +226,7 @@ public interface Saml2AuthenticationRequestFactory {
 [[samllogin-sample-boot]]
 === Spring Boot 2.x Sample
 
-We are currently working with the the Spring Boot team on the
+We are currently working with the Spring Boot team on the
 https://github.com/spring-projects/spring-boot/issues/18260[Auto Configuration for Spring Security SAML Login].
 In the meantime, we have provided a Spring Boot sample that supports a Yaml configuration.