Improve after.sh documentation

The lack of documentation makes this script, that is run after homestead
was brought up for the first time (rudimentary provisioning script),
very hard to maintain. Already some constructions raise questions:

1. Do we want to install nvm from githubusercontent.com? Or can we pull
it from a trusted repository (apt?)
2. Why is node pinned to version 8.9.1? Maybe make this configurable?
3. Why was the xon statement used?

Story short, Ansible might be a good replacement here?

homestead/after.sh

@@ -8,17 +8,32 @@
 # to apply, you may also create user-customizations.sh,
 # which will be run after this script.
 
+# Start by updating the apt dependencies making the base box up to date
 sudo apt update
 DEBIAN_FRONTEND=noninteractive sudo apt upgrade -y
-DEBIAN_FRONTEND=noninteractive sudo apt install plantuml -y
 
-cd /home/vagrant/code
+# Install the plantuml dependency (used to generate UML diagrams in the markdown files
+DEBIAN_FRONTEND=noninteractive sudo apt install plantuml -y
 
+# Use our onw PHP.ini
 sudo cp /home/vagrant/code/homestead/php.ini /etc/php/7.2/mods-available/custom.ini
+
+# Use PHP 7.2 by default in our environment
 sudo phpenmod -v 7.2 custom
+
+
+# Aplly the following changes in the code directory
+cd /home/vagrant/code
+
+# Install composer dependencies
 COMPOSER_MEMORY_LIMIT=-1 composer install
+
 xon
+
+# On successive logins to the vagrant box, automatically CD to the code directory
 echo 'cd /home/vagrant/code' >> ~/.profile
+
+# Download and install NVM (ability to switch node/npm versions)
 curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.34.0/install.sh | bash
 export NVM_DIR="$HOME/.nvm"
 [ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm