Pr docs introduction
Pr docs introduction

Small suggestions to basics/introduction doc

Author: Asko Kauppi <akauppi@gmail.com>

Reviewers: Sijie Guo <sijie@apache.org>

Closes #72 from akauppi/pr-docs-introduction

sijie/incubator-distributedlog,sijie/incubator-distributedlog,sijie/incubator-distributedlog,sijie/incubator-distributedlog,sijie/incubator-distributedlog