finish busybox.1 renaming

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/docs/.gitignore b/docs/.gitignore
index 9d1b7c2..11d6163 100644
--- a/docs/.gitignore
+++ b/docs/.gitignore
@@ -1,4 +1,4 @@
-/BusyBox.1
+/busybox.1
 /BusyBox.html
 /BusyBox.txt
 /busybox.pod