Update Introduction to the field of reliability engineering.rst

docs/Introduction to the field of reliability engineering.rst

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 Introduction to the field of reliability engineering
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-Reliability Engineering is amazing
+Reliability engineering is a field of study that deals with the estimation, prevention, and management of failures by combining statistics, risk analysis, and physics. By understanding how failures may occur or have occurred, we are able to better predict the lifecycle of a product and thereby manage the risks associated with its failure. All engineering systems, components, and structures will eventually fail, and knowing how and when that failure will occur is of great interest to the owners and operators of those systems. 
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+Everyone is acutely aware of the importance of reliability, particularly when something doesn't work at a time we expect it to. Whether it be your car not starting, your computer's hard drive failing, or the chance of a contamination leak from a nuclear power plant, system failure is something we all want to avoid, and when it can't be avoided, we at least want to know when it is likely to occur.
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+We define a reliable system as one that performs a required function without failure under stated conditions for a stated period of time.