[doc] #107: Improve Argos tutorial.

doc/argos.md

-## Integrate it on a dropdown menu to the panel
+## Install as a drop-down for GNOME Shell with Argos
 Under GNOME Shell, with [Argos](https://github.com/p-e-w/argos) extension:
 
 - [Install Argos](https://github.com/p-e-w/argos#installation)
-- Put inside `~/.config/argos/silkaj.30s.sh`:
+- Inside `~/.config/argos/silkaj.30s.sh` put:
 
 ```bash
 #!/usr/bin/env bash
 /path/to/silkaj/silkaj argos
 ```
 
-Add execution premission:
+Add execution permission:
 ```bash
 chmod u+x ~/.config/argos/silkaj.30s.sh
 ```
 
-Argos should the script and reload it every 30 seconds.
+Argos will run the script every 30 seconds.