Added update-readmes.sh to change .zip links in README.mds.

update-readmes.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+# Needs gnu-sed on macOS for inplace replacement
+# brew install --with-default-names gnu-sed
+set -e
+
+if [ -z "$1" ] 
+	then
+		echo "Usage: ./update-readmes.sh <from-branch> <to-branch>"
+		echo "Example: ./update-readmes.sh 3.6 3.7"
+		exit
+fi
+
+if [ -z "$2" ] 
+	then
+		echo "Usage: ./update-readmes.sh <from-branch> <to-branch>"
+		echo "Example: ./update-readmes.sh 3.6 3.7"
+		exit
+fi
+
+find . -type f -name 'README.md' | while read line; do
+	echo "Updating $line"
+	sed -i "s,https://github.com/EsotericSoftware/spine-runtimes/archive/$1.zip,https://github.com/EsotericSoftware/spine-runtimes/archive/$2.zip,g" $line
+done