fix(release): add some hints to the release script

Author: hanxiao

release.sh

@@ -3,6 +3,7 @@
 # Requirements
 # brew install hub
 # npm install -g git-release-notes
+# pip install twine
 
 set -e
 
@@ -95,6 +96,10 @@ if [[ -z "${BOT_URL}" ]]; then
   exit 1;
 fi
 
+if [[ -z "${GITHUB_TOKEN}" ]]; then
+  printf "GITHUB_TOKEN is not set! Need to export GITHUB_TOKEN=xxx"
+  exit 1;
+fi
 
 #$(grep "$VER_TAG" $CLIENT_CODE | sed -n 's/^.*'\''\([^'\'']*\)'\''.*$/\1/p')
 OLDVER=$(git tag -l | sort -V |tail -n1)