Added reference to Teachable

Author: tommyoswinwilliams

README.md

@@ -27,7 +27,7 @@ The Command Line Murder
 
 There's been a murder in Terminal City, and TCPD needs your help.
 
-Before you start, skim through the required materials in the Command Line and Version Control sections of your PreCourse repo. Use it as a reference while working through the case.
+Before you start, skim through the required materials in the Command Line and Version Control sections of the PreCourse on Teachable. Use it as a reference while working through the case.
 
 Now with your Terminal at hand you're ready to start. A couple of ground rules first:
 
@@ -46,11 +46,8 @@ Next you need to download those files to your machine so that you can edit them.
 
 ## Step 2: Investigate
 
-Each step of your investigation will contain a reference to the **Detective Handbook** at the top. Each page of the Detective Handbook contains the description of the commands you will need to complete that particular step. You can view them in the Terminal:
+Each step of your investigation will contain a reference to the **Detective Handbook** at the top. Each page of the Detective Handbook contains the description of the commands you will need to complete that particular step.
 
-```bash
-Reference: ./detective_handbook/getting_started.md
-```
 Open a Terminal, go to the location of the files (using the `cd` command), and start by reading the file 'step0'.
 
 One way you can do this is with following command: