Fix badge (#50)

README.md

@@ -5,13 +5,13 @@
 Quiver is a library that builds upon [Arrow](https://arrow-kt.io/) to make functional programming in Kotlin even 
 more accessible & delightful.
 
+[<img src="https://img.shields.io/nexus/r/app.cash.quiver/lib.svg?label=latest%20release&server=https%3A%2F%2Foss.sonatype.org"/>](https://central.sonatype.com/namespace/app.cash.quiver)
+
 Main features include:
 * `Outcome` type for modelling the presence, absence or error state of a value.
 * Extension methods on `Option`, `List`, `Validated` and `Either` for improved error handling, combinators and interoperability with other Arrow and Kotlin types.
 * Extension methods on suspended functions to allow for seemless retries of operations.
 
-[<img src="https://img.shields.io/maven-central/v/app.cash.quiver/lib.svg?label=latest%20release"/>](https://central.sonatype.com/namespace/app.cash.quiver)
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 There are two published builds.
 
 * `lib` contains types and functions to provide additional functional programming idioms over and above what is available from Arrow.