added Spring Boot 2 Hikary configuartions to README

[brocchini]

It took me a awhile to get this simple configuration working with Spring Boot. I'm adding this to hopefully save other people's time.

[coveralls]

Pull Request Test Coverage Report for Build 281

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 47.963%

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Totals
Change from base Build 280:	0.0%
Covered Lines:	471
Relevant Lines:	982

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💛 - Coveralls