Update the guide for new metrics in 18.0.0.3

[gkwan-ibm]

We should add a part to tell users to view/retrieve JVM metrics by https://localhost:/metrics/base

Also, add a new part to teach users to view/retrieve Liberty metrics by https://localhost:/metrics/vendor when enable mpMetrics-1.1 and monitor-1.0

<featureManager>
    <feature>mpMetrics-1.1</feature> 
    <feature>monitor-1.0</feature>
</featureManager>

<mpMetrics authentication=“true|false’/>

[evelinec]

Fixed in #84