Update the documentation

Author: allenwux

README.md

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 ## TPC-C in Python for MongoDB
+Approved in July of 1992, TPC Benchmark C is an on-line transaction processing (OLTP) benchmark. TPC-C is more complex than previous OLTP benchmarks such as TPC-A because of its multiple transaction types, more complex database and overall execution structure. TPC-C involves a mix of five concurrent transactions of different types and complexity either executed on-line or queued for deferred execution. The database is comprised of nine types of tables with a wide range of record and population sizes. TPC-C is measured in transactions per minute (tpmC). While the benchmark portrays the activity of a wholesale supplier, TPC-C is not limited to the activity of any particular business segment, but, rather represents any industry that must manage, sell, or distribute a product or service.
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+To learn more about TPC-C, please see the [TPC-C](https://www.tpc.org/tpcc/) documentation.
 
 This repo is an experimental variant of Python TPC-C implementation based on the original [here](http://github.com/apavlo/py-tpcc).