Make it clearer that pip installation needs to be run in a terminal

Sam Hames · Sam Hames · commit 7dbdf1fe7863 · 2022-03-09T16:35:49.000+10:00
As it doesn't currently make it clear where that command needs to
be run, and only people who have used a command line before will
be able to infer that.
diff --git a/docs/README.md b/docs/README.md
@@ -8,7 +8,7 @@ See the `twarc` documentation for running commands: [twarc2](twarc2_en_us.md) an
 
 ## Install
 
-If you have python installed, you can install twarc using:
+If you have python installed, you can install twarc from a terminal (such as the Windows Command Prompt available in the "start" menu, or the [OSX Terminal application](https://support.apple.com/en-au/guide/terminal/apd5265185d-f365-44cb-8b09-71a064a42125/mac)):
 
 ```
 pip3 install twarc
diff --git a/docs/twarc2_en_us.md b/docs/twarc2_en_us.md
@@ -35,7 +35,7 @@ generate an access token and access token secret. With these four variables
 in hand you are ready to start using twarc.
 
 1. install [Python 3](http://python.org/download)
-2. [pip](https://pip.pypa.io/en/stable/installing/) install twarc:
+2. [pip](https://pip.pypa.io/en/stable/installing/) install twarc from a terminal (such as the Windows Command Prompt available in the "start" menu, or the [OSX Terminal application](https://support.apple.com/en-au/guide/terminal/apd5265185d-f365-44cb-8b09-71a064a42125/mac)):
 
 ```
 pip install --upgrade twarc
