Fix broken links in reconnection manual

Those links redirect to internal API which is not a part of the
generated javadoc, leading to 404 on visit.
Instead redirect to code on github.

Author: Bouncheck

manual/core/reconnection/README.md

@@ -103,7 +103,7 @@ Note that the session is not accessible until it is fully ready: the `CqlSession
 call — or the future returned by `buildAsync()` — will not complete until the connection
 was established.
 
-[ConstantReconnectionPolicy]:    https://docs.datastax.com/en/drivers/java/4.17/com/datastax/oss/driver/internal/core/connection/ConstantReconnectionPolicy.html
+[ConstantReconnectionPolicy]:    https://github.com/scylladb/java-driver/blob/scylla-4.19.0.x/core/src/main/java/com/datastax/oss/driver/internal/core/connection/ConstantReconnectionPolicy.java
 [DriverContext]:                 https://docs.datastax.com/en/drivers/java/4.17/com/datastax/oss/driver/api/core/context/DriverContext.html
-[ExponentialReconnectionPolicy]: https://docs.datastax.com/en/drivers/java/4.17/com/datastax/oss/driver/internal/core/connection/ExponentialReconnectionPolicy.html
+[ExponentialReconnectionPolicy]: https://github.com/scylladb/java-driver/blob/scylla-4.19.0.x/core/src/main/java/com/datastax/oss/driver/internal/core/connection/ExponentialReconnectionPolicy.java
 [ReconnectionPolicy]:            https://docs.datastax.com/en/drivers/java/4.17/com/datastax/oss/driver/api/core/connection/ReconnectionPolicy.html