docs: Hoist Spec out of try-with-resources in README examples

Surrounding text builds the server from spec, so it must be reachable
after the try block. Use an uninitialized declaration rather than
null-init — javac's definite-assignment analysis covers the only
non-throwing path.

Author: thced

README.md

@@ -128,17 +128,19 @@ public class YourServerLauncher {
 To load a spec from the classpath (including from inside a JAR) use the `InputStream` overloads:
 
 ``` java
+Spec spec;
 try (InputStream in = YourServerLauncher.class.getResourceAsStream("/openapi.json")) {
-  Spec spec = Spec.fromJson(in);   // Gson on the classpath
+  spec = Spec.fromJson(in);   // Gson on the classpath
 }
 ```
 
 The matching `Spec.fromYaml(InputStream)` uses SnakeYAML. Both close the stream before returning. If you can't (or don't want to) depend on Gson/SnakeYAML, supply your own parser:
 
 ``` java
 ObjectMapper jackson = new ObjectMapper();
+Spec spec;
 try (InputStream in = YourServerLauncher.class.getResourceAsStream("/openapi.json")) {
-  Spec spec = Spec.fromJson(in, bytes -> jackson.readValue(bytes, Map.class));
+  spec = Spec.fromJson(in, bytes -> jackson.readValue(bytes, Map.class));
 }
 ```