Add in HTTP redirect documentation

Author: OllieJC

001-http-redirect/README.md

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+# 001-http-redirect
+
+The best implementation is to utilise a HTTP redirect to the central security.txt file.
+
+```
+< HTTP/1.1 302 Found
+< Location: https://vulnerability-reporting.service.security.gov.uk/.well-known/security.txt
+```
+
+See below for various implementation examples:
+- [Node.js Express.js](#nodejs-expressjs)
+- [Node.js 'http'](#nodejs-http)
+- [Python Flask](#python-flask)
+
+Additionally, see [002-faas-edge-code](../002-faas-edge-code) for code to implement at your CDN edge to perform the HTTP redirect. 
+
+## Node.js Express.js
+
+``` js
+const express = require('express')
+const app = express()
+const port = 3000
+
+const sectxt_pathregex = /^(\/.well[-_]known)?\/security(\.txt)?/
+const sectxt_location = 'https://vulnerability-reporting.service.security.gov.uk/.well-known/security.txt'
+
+app.get(sectxt_pathregex, (req, res) => {
+  res.redirect(sectxt_location)
+})
+
+app.get('/', (req, res) => {
+  res.send('OK')
+})
+
+app.listen(port, () => {
+  console.log(`Example app listening on port ${port}`)
+})
+```
+
+## Node.js 'http'
+
+``` js
+var port = 3000;
+var http = require('http');
+var url = require('url');
+var sectxt_pathregex = /^(\/.well[-_]known)?\/security(\.txt)?/;
+var sectxt_location = 'https://vulnerability-reporting.service.security.gov.uk/.well-known/security.txt';
+
+var server = http.createServer(function(req, res) {
+  var parsedUrl = url.parse(req.url);
+  if(parsedUrl.pathname.match(sectxt_pathregex)) {
+    res.writeHead(302, {'Location': sectxt_location});
+    res.end();
+    return;
+  }
+});
+
+server.listen(port);
+```
+
+## Python Flask
+
+``` python
+import os
+from flask import Flask, redirect
+
+app = Flask(__name__)
+SECTXT_LOCATION = 'https://vulnerability-reporting.service.security.gov.uk/.well-known/security.txt'
+
+@app.route("/", methods=["GET"])
+def root():
+    return "OK"
+
+@app.route("/.well-known/security.txt", methods=["GET"])
+@app.route("/security.txt", methods=["GET"])
+def securitytxt():
+    return redirect(SECTXT_LOCATION)
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", port=int(os.getenv("PORT", "3000")))
+```

003-html-redirect/README.md

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+# 003-html-redirect
+
+TBC