Make paths relative, not absolute

[perpil]

Fix the cd: no such file or directory: /00-baseCore error when following steps in the README:

cd /00-baseCore
sam build
sam deploy --guided
cd: no such file or directory: /00-baseCore

Description

The absolute paths in the README don't work, switch to use relative paths so you can copy/paste.

Related Issue

Issue 16

Motivation and Context

Remove some friction from getting started

How Has This Been Tested?

I ran the updated commands to install

Screenshots (if appropriate):

N/A