Update README.md

fixed typo

README.md

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-idibu integration's APIs
+idibu integration APIs
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 idibu provides you with means of using our funtionality precisely how you would like it to run with your software! One can choose from a variety of integration options. Those can either quickly introduce multiposting for you clients (our current record holder took 2 days to roll-out a working integration!) or you can rebuild almost the whole of idibu inside your product.