toplevel .gitignore: start with a simple one

as putting too much in toplevel is seen as bad style
anyway this one allows to get a small sense of
git status

Signed-off-by: maximilian attems <max@stro.at>
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1ab997c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,9 @@
+#
+# NOTE! Don't add files that are generated in specific
+# subdirectories here. Add them in the ".gitignore" file
+# in that subdirectory instead.
+#
+# Normal rules
+#
+*.o
+*.o.cmd