Add Intellij generated project files to git ignore list

Also add comments to categorise list of ignored files

Change-Id: I8afe9e5cb86e2dbc5d69d03ff009e81719d2d103
diff --git a/.gitignore b/.gitignore
index a240767..4b436ab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,10 +1,15 @@
-/eclipse-out
-/target
 /.bazel_path
-/.classpath
-/.project
-/.DS_Store
+# Ignore outputs generated during Bazel build
+/target
+# Ignore all bazel-* symlinks
 /bazel-*
+# macOS-specific excludes
+/.DS_Store
+# Ignore files generated by IDEs
 *.iml
 /.apt_generated/
 /.apt_generated_tests/
+/.classpath
+/.ijwb
+/.project
+/eclipse-out