SSO samples do not work with older IS versions

[darshanasbg]

Older versions (5.3.0) of IS use different keystore compared to one that used in the later versions (5.7.0).

Need to update readmes on updating the keystore if it's needed

[darshanasbg]

ex:
cp ~/wso2is-5.3.0/repository/resources/security/wso2carbon.jks ~/apache-tomcat-8.5.33/webapps/saml2-web-app-pickup-manager.com/WEB-INF/classes/wso2carbon.jks