Merge pull request #217 from alan-turing-institute/more-docs-tweaks

Update docs

docs/getting-started.md

@@ -26,9 +26,9 @@ Environment variables are defined in your Terminal configuration file. Since we
 
 To do this, run the following command:
 ```console
-$ echo "export SHELL_CONFIG=" $(find ~/.*shrc -maxdepth 0 | head -n 1) | sed 's/= /=/g' >> $(find ~/.*shrc -maxdepth 0 | head -n 1)
+$ SHELL_CONFIG=$(find ~/.*shrc -maxdepth 0 | head -n 1) && echo "export SHELL_CONFIG=$SHELL_CONFIG" >> $SHELL_CONFIG
 ```
-**Then close and reopen the Terminal window that you're working in**, so that the change takes effect. Now check that the new environment variable exists:
+Now check that the new environment variable exists:
 ```console
 $ echo $SHELL_CONFIG
 ```

docs/ion.md

@@ -59,17 +59,17 @@ In all cases, administrator privileges are required.
 
 ### Prerequisites
 
+!!! info "Create the `SHELL_CONFIG` environment variable"
+
+    Before continuing, make sure you have created the `SHELL_CONFIG` environment variable by following the instructions on the [Getting Started](getting-started.md#environment-variables) page.
+
 Run the following commands to set up your environment.
 
 === "Linux"
 
-    Update the package lists on your machine:
-    ```console
-    $ sudo apt update
-    ```
-    and install essential build tools:
+    Update the package lists on your machine and install essential build tools:
     ```console
-    $ sudo apt install build-essential
+    $ sudo apt update && sudo apt install build-essential
     ```
     Install Git:
     ```console