Add .gitignore (#99)

* Add .gitignore

* Update .gitignore

Co-authored-by: Brandon Fergerson <[email protected]>

Author: MrMineO5

.gitignore

@@ -0,0 +1,16 @@
+# Ignore artifacts
+build/
+docker/e2e/spp-*.jar
+
+# Ignore downloaded skywalking agent
+e2e/apache-skywalking-java-agent-*.tgz
+e2e/skywalking-agent/
+
+# Ignore download s++ probe
+e2e/spp-probe-*.jar
+
+# Ignore IDE files
+.idea/
+
+# Ignore .gradle directory
+.gradle/