update git hook 'pre-commit'

.githooks/pre-commit

@@ -3,9 +3,8 @@
 # Replace `last_modified_at` timestamp with current time
 # https://mademistakes.com/notes/adding-last-modified-timestamps-with-git/
 
-git diff --cached --name-status | grep -E -i "^(A|M).*\.(md)$" | while read a b; do
-  cat $b | sed "/+++.*/,/+++.*/s/^lastmod.*$/lastmod = '$(date -u "+%Y-%m-%dT%H:%M:%S%z")'/" > tmp
+git diff --cached --name-status | egrep -i "^(A|M).*\.(md)$" | while read a b; do
+  cat $b | sed "/---.*/,/---.*/s/^lastmod:.*$/lastmod: $(date -u "+%Y-%m-%dT%H:%M:%S%z")/" > tmp
   mv tmp $b
   git add $b
 done
-