Update links to native image docs (#35)

Author: rdipardo

README.md

@@ -48,10 +48,10 @@ More libraries to come (*PRs are welcome*).
 
 Interesting GraalVM documentation to build native-images:
 
-  - Understand [Class Initialization in Native Image](https://github.com/oracle/graal/blob/master/substratevm/CLASS-INITIALIZATION.md)
-  - [Assisted Configuration of Native Image Builds](https://github.com/oracle/graal/blob/master/substratevm/CONFIGURE.md)
-  - [URL Protocols on Substrate VM](https://github.com/oracle/graal/blob/master/substratevm/URL-PROTOCOLS.md) for `http` and `https`
-  - [JCA Security Services on Substrate VM](https://github.com/oracle/graal/blob/master/substratevm/JCA-SECURITY-SERVICES.md)
+  - Understand [Class Initialization in Native Image](https://github.com/oracle/graal/blob/master/substratevm/ClassInitialization.md)
+  - [Assisted Configuration of Native Image Builds](https://github.com/oracle/graal/blob/master/substratevm/BuildConfiguration.md#assisted-configuration-of-native-image-builds)
+  - [URL Protocols on Substrate VM](https://github.com/oracle/graal/blob/master/substratevm/URLProtocols.md) for `http` and `https`
+  - [JCA Security Services on Substrate VM](https://github.com/oracle/graal/blob/master/substratevm/JCASecurityServices.md)
 
 
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