IoT Gateways: typo with the cd into repo step (#688)

* IoT Gateways: typo with the cd into repo step 

fixed minor typo in the step that changes into this tutorial's directory

* fix another instance of incorrect directory name

tutorials/cloud-iot-gateways-rpi/index.md

@@ -99,7 +99,7 @@ To set up your gateway:
 1. Clone the following repository and change into the directory for this tutorial's code:
 
         git clone https://github.com/GoogleCloudPlatform/community.git
-        cd community/tutorials/cloud-iot-gateways-pi
+        cd community/tutorials/cloud-iot-gateways-rpi
 
 2. Generate an RS256 public/private key pair by running the following:
 
@@ -155,7 +155,7 @@ In this tutorial, you'll use a [Raspberry Pi][rpi] to manage the LED/temperature
 8. Clone the following repository and change into the directory for this tutorial's code:
 
         git clone https://github.com/GoogleCloudPlatform/community.git
-        cd community/tutorials/cloud-iot-gateways-pi
+        cd community/tutorials/cloud-iot-gateways-rpi
 
 9. Install Python dependencies by running the following: