Modification du .gitignore pour `loot/*/ext`.

.gitignore

@@ -1,4 +1,7 @@
-loot/certs/*
+loot/*
-!loot/certs/.gitkeep
+!loot/certs
-loot/csr/*
+!loot/certs/ext
-!loot/csr/.gitkeep
+!loot/certs/ext/.gitkeep
+!loot/csr
+!loot/csr/ext
+!loot/csr/ext/.gitkeep