.gitignore: Adds .idea to ignorefile.

Change-Id: I07d9947b7dc589471de160b5f9d5a0794ac111f6
Signed-off-by: Luka Strizic <lstrz@google.com>
diff --git a/.gitignore b/.gitignore
index fd9ea53..a749464 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@
 !subprojects/*.wrap
 
 .vscode
+.idea