Update installation documentation to improve clarity and formatting

docs/source/installation.md

@@ -21,15 +21,15 @@ python3 -m venv nanomotif
 source nanomotif/bin/activate
 pip install nanomotif
 ```
-
+---
 ## Check Installation
 Once installed, the installation can be checked by running:
 ```shell
 nanomotif check-installation
 ```
 This runs a test run on a small dataset, ensuring everything works.
 
-
+---
 ## MTase-linker Installation
 The MTase-Linker module has additional dependencies that are not automatically installed with Nanomotif. Therefore, before using this module, you must manually install these dependencies using the `MTase-linker install` command.
 The `MTase-linker` module requires that conda is available on your system.