maintner/slurpgit: delete README.md for otherwise empty directory

This README was an accident. I had an early prototype of maintner on
my local disk as slurpgit.go (before it was named maintner). Because
it was on my disk, when I ran x/build/update-readmes.go, it created
this directory.

Fixes golang/go#30744

Change-Id: I8a7807a8c7c0faaf31124cba1401d7c96b0bdbdc
Reviewed-on: https://go-review.googlesource.com/c/build/+/166878
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/maintner/slurpgit/README.md b/maintner/slurpgit/README.md
deleted file mode 100644
index bdc34e2..0000000
--- a/maintner/slurpgit/README.md
+++ /dev/null
@@ -1,7 +0,0 @@
-<!-- Auto-generated by x/build/update-readmes.go -->
-
-[![GoDoc](https://godoc.org/golang.org/x/build/maintner/slurpgit?status.svg)](https://godoc.org/golang.org/x/build/maintner/slurpgit)
-
-# golang.org/x/build/maintner/slurpgit
-
-