Update README.md

[l4rot]

added the memstore feature to the cargo.toml, since the example won't work without that activated.

Description of change

After trial and error periods and reinstalling my env I noticed that the memstore feature hasn't been added to the cargo.toml in the example, hence why it did not compile for me initially. added it to the readme to safe other people from having a headache over the same issue.

Links to any relevant issues

Be sure to reference any related issues by adding fixes issue #.

Type of change

Add an x to the boxes that are relevant to your changes.

• Bug fix (a non-breaking change which fixes an issue)
• Enhancement (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Fix

How the change has been tested

The example project finally ran.

Change checklist

Add an x to the boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[abdulmth]

Looks good to me, thanks for the PR.