Minor update to the contributing doc (#707)

* Minor update to the contributing doc

* Update CONTRIBUTING.md

Set core.autocrlf locally.

Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

* Update CONTRIBUTING.md

Add more clarity.

Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

* Use .gitattributes to make spotless respect line endings

Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

.gitattributes

@@ -0,0 +1,5 @@
+* text=auto eol=lf
+
+*.bat text eol=crlf
+*.cmd text eol=crlf
+

CONTRIBUTING.md

@@ -65,7 +65,7 @@ still access helper classes from bootstrap classloader.
 #### Agent jar structure
 
 If you now look inside
-`java-agent/build/libs/opentelemetry-javaagent-<version>-all.jar`, you will see the
+`opentelemetry-javaagent/build/libs/opentelemetry-javaagent-<version>-all.jar`, you will see the
 following "clusters" of classes:
 
 - `inst/` - contains `agent-tooling` module and `instrumentation` submodules, loaded and isolated inside
@@ -86,10 +86,23 @@ snapshot builds of the `master` branch. They are available from
 
 Build using Java 11:
 
-```gradle assemble```
+```bash
+java -version
+```
+
+```bash
+./gradlew assemble
+```
+
+and then generate the -all artifact
+
+```bash
+./gradlew :opentelemetry-javaagent:shadowJar
+```
 
 and then you can find the java agent artifact at
-`java-agent/build/lib/opentelemetry-javaagent-<version>-all.jar`.
+
+`opentelemetry-javaagent/build/lib/opentelemetry-javaagent-<version>-all.jar`.
 
 ### Testing