Deprecate old guides

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

guide/deprecated/chaining_functions.md

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+# Chaining OpenFaaS functions
+
+We will discuss client-side piping, server-side piping and the "function director" pattern.
+
+## Client-side piping
+
+The easiest way to chain functions is to do it on the client-side via your application code or a `curl`.
+
+Here is an example:
+
+We pipe a string or file into the markdown function, then pipe it into a Slack function
+
+```
+$ curl -d "# test" localhost:8080/function/markdown | \
+  curl localhost:8080/function/slack --data-binary -
+```
+
+You could also do this via code, or through the `faas-cli`:
+
+```
+$ echo "test" | faas-cli invoke markdown | \
+faas-cli invoke slack
+```
+
+## Server-side access via gateway
+
+On the server side you can access any other function by calling it on the gateway over HTTP.
+
+### Function A calls B
+
+Let's say we have two functions:
+* geolocatecity - gives a city name for a lat/lon combo in JSON format
+* findiss - finds the location of the International Space Station then pretty-prints the city name by using the `geolocatecity` function
+
+findiss Python 2.7 handler:
+
+```
+import requests
+
+def get_space_station_location():
+    return {"lat": 0.51112, "lon": -0.1234}
+
+def handler(st):
+    location = get_space_station_location()
+    r = requests.post("http://gateway:8080/function/geolocatecity", location)
+
+    print("The ISS is over the following city: " + r.content)
+```
+
+
+### Function Director pattern
+
+In the Function Director pattern - we create a "wrapper function" which can then either pipes the result of function call A into function call B or compose the results of A and B before returning a result. This approach saves on bandwidth and latency vs. client-side piping and means you can version both your connector and the functions involved.
+
+Take our previous example:
+
+```
+$ curl -d "# test" localhost:8080/function/markdown | \
+  curl localhost:8080/function/slack --data-binary -
+```
+
+markdown2slack Python 2.7 handler:
+
+```
+import requests
+
+def handler(req):
+    
+    markdown = requests.post("http://gateway:8080/function/markdown", req)
+    slack_result = requests.post("http://gateway:8080/function/slack", markdown.content)
+
+    print("Slack result: " + str(slack_result.status_code))
+```
+
+Practical example:
+
+GitHub sends a "star" event to tweetfanclub function, tweetfanclub uses get-avatar to download the user's profile picture - stores that in an S3 bucket, then invokes tweetstargazer which tweets the image. A polaroid effect is added by a "polaroid" function.
+
+This example uses a mix of regular binaries such as ImageMagick and Python handlers generated with the FaaS-CLI.
+
+* [GitHub to Twitter Fanclub](https://github.com/alexellis/faas-twitter-fanclub/blob/master/README.md)
+
+## Asynchronous call-backs
+
+If you invoke a function asynchronously you have two options for getting the result back:
+
+* Update the function
+
+You can update your code to call another function / store state in another service
+
+* X-Callback-Url
+
+If you set a header for `X-Callback-Url` then that will be invoked after the function has run, [read more](https://github.com/openfaas/faas/blob/1aa6270fcc274cc36d90e0a9e4caa3eb71912ae0/guide/asynchronous.md#call-a-function)