Fix Readme.md of spring-helloworld sample

[kasunsiyambalapitiya]

Purpose

Fixing the existing inconsistency with the sample code and the explanation in README.md of spring-helloworld sample. Resolves #510

Goals

To make the sample code and the explanation of README.md of the spring-helloworld sample consistent.

Approach

The doc and the sample code was modified to be inconsistent.

User stories

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Release note

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Documentation

Documentation of spring-helloworld sample is the one being fixed.

Training

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Certification

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Marketing

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Automation tests

• Unit tests
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• Integration tests
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Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes
• Ran FindSecurityBugs plugin and verified report? N/A
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? yes

Samples

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Related PRs

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Migrations (if applicable)

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Test environment

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Learning

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