Add a how to run the samples section to Samples chapter in docs

[asaikali]

Chapter 7 Samples does not provide any guidance on how to run the samples. The samples have dependencies based on the gradle project for example

apply plugin: 'io.spring.convention.spring-sample-boot'

dependencies {
    compile project(':spring-security-config')
    compile project(':spring-security-web')
    compile 'org.springframework.boot:spring-boot-starter-thymeleaf'
    compile 'org.springframework.boot:spring-boot-starter-web'
    compile 'org.thymeleaf.extras:thymeleaf-extras-springsecurity5'

    testCompile project(':spring-security-test')
    testCompile 'org.springframework.boot:spring-boot-starter-test'
}

To run the samples you can't just import that one project into the IDE you need to import all of spring security project into the IDE. Also the link to the samples from the docs points to the master branch, the user might be on a different version of spring security and so the samples as shown in master might not be useful to the reader.

I propose adding a section to the docs on how to run the samples. The section should should cover.

• software prereqs to run the sample (Java version), IDE ... etc
• instructions on how to import and run the samples
• instructions on how to contribute fixes and improvements to the samples to make them more useful to users.

[rwinch]

This is once again a good idea. However, there is going to be some work done to split up the samples so they can run separate of Spring Security. I created gh-8217 to track that work