README: improve etag example with escaping of the filename

Use the same base filename as the feed file, because sfeed_update replaces '/'
in names with '_':

	filename="$(printf '%s' "$1" | tr '/' '_')"

This fixes the example for fetching feeds with names containing '/'.

Reported by __20h__, thanks!

1 files changed, 1 insertions, 1 deletions

diff --git a/README b/README
index 3cc7ca2..fa8e740 100644
--- a/README
+++ b/README
@@ -588,7 +588,7 @@ the --etag-save and --etag-compare options:
 
 	# fetch(name, url, feedfile)
 	fetch() {
-		etag="$HOME/.sfeed/etags/$1"
+		etag="$HOME/.sfeed/etags/$(basename "$3")"
 		curl --etag-save "${etag}" --etag-compare "${etag}" "$2"
 	}