Fix type in config.cfg in pipelines,md

The file extension given didn't match the examples

Author: DustyShap

source/pipelines.md

@@ -200,7 +200,7 @@ We will be using the Tweepy library for this (docs here [https://tweepy.readthed
 Let's start with an example to collect some Tweets from your public timeline
 (for details on the Tweet object visit [the API docs](https://developer.twitter.com/en/docs/tweets/data-dictionary/overview/intro-to-tweet-json#tweetobject))
 
-🚦 The first step will be to create a config file (`config.cgf`) with your Twitter API tokens.
+🚦 The first step will be to create a config file (`config.cfg`) with your Twitter API tokens.
 ```
 [twitter]
 consumer_key = xxxxxxxxxxxxxxxxxx
@@ -628,4 +628,4 @@ if __name__ == "__main__":
 
 🚦In pairs discuss:
 - How would you run the two scripts together?
-- Try and create the pipeline: `stream_twitter.py` -> `analyse_twitter.py`
+- Try and create the pipeline: `stream_twitter.py` -> `analyse_twitter.py`