Add example for builder podspec (#1374)

examples/spec-example/hello-spec-exmaple/hello/build.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+set -e
+
+# check syntax
+python3 -m compileall -l ${SRC_PKG}
+
+# install deps
+pip3 install -r ${SRC_PKG}/requirements.txt -t ${SRC_PKG} && cp -r ${SRC_PKG} ${DEPLOY_PKG}

examples/spec-example/hello-spec-exmaple/hello/hello.py

@@ -0,0 +1,4 @@
+import yaml
+
+def main():
+    return "hello, world!!\n"

examples/spec-example/hello-spec-exmaple/hello/requirements.txt

@@ -0,0 +1 @@
+pyyaml