docs: rephrase initial doc section (#3205)

docs/src/main/paradox/index.md

@@ -1,6 +1,6 @@
 # Alpakka Documentation
 
-The [Alpakka project](https://doc.akka.io/docs/alpakka/current/) is an open source initiative to implement stream-aware and reactive integration pipelines for Java and Scala. It is built on top of [Akka Streams](https://doc.akka.io/docs/akka/current/stream/index.html), and has been designed from the ground up to understand streaming natively and provide a DSL for reactive and stream-oriented programming, with built-in support for backpressure. Akka Streams is a [Reactive Streams](https://www.reactive-streams.org/) and JDK 9+ [java.util.concurrent.Flow](https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/Flow.html)-compliant implementation and therefore [fully interoperable](https://doc.akka.io/docs/akka/current/general/stream/stream-design.html#interoperation-with-other-reactive-streams-implementations) with other implementations.
+The [Alpakka project](https://doc.akka.io/docs/alpakka/current/) is an initiative to implement stream-aware and reactive integration pipelines for Java and Scala. It is built on top of [Akka Streams](https://doc.akka.io/docs/akka/current/stream/index.html), and has been designed from the ground up to understand streaming natively and provide a DSL for reactive and stream-oriented programming, with built-in support for backpressure. Akka Streams is a [Reactive Streams](https://www.reactive-streams.org/) and JDK 9+ [java.util.concurrent.Flow](https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/Flow.html)-compliant implementation and therefore [fully interoperable](https://doc.akka.io/docs/akka/current/general/stream/stream-design.html#interoperation-with-other-reactive-streams-implementations) with other implementations.
 
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