certbot(role): move arguments documentation into README

Do this to match how it's done in newer roles.

roles/certbot/README.md

@@ -8,7 +8,15 @@ Also see the following documentation for a full How-to on how to get certificate
 
 ## Required Arguments
 
-For the required arguments look at the [`argument_specs.yaml`](./meta/argument_specs.yaml).
+- `certbot__acme_account_email_address`: The E-Mail address to use for the ACME account.
+- `certbot__certificate_domains`: The domains for which to obtain a certificate.
+
+## Optional Arguments
+
+- `certbot__http_01_port`: The port number the bot listens on. Should be `80` if directly exposed to the internet.  
+   Defaults to `31820` (for the public-reverse-proxy setup).
+- `certbot__new_cert_commands`: A list of commands to execute after getting a new certificate. Will be added into a bash script.  
+  Defaults to the empty list (`[ ]`).
 
 ## `hosts`
 

roles/certbot/meta/argument_specs.yaml

@@ -2,25 +2,17 @@ argument_specs:
   main:
     options:
       certbot__acme_account_email_address:
-        description: The E-Mail address to give to certbot for the ACME account.
         type: str
         required: true
       certbot__certificate_domains:
-        description: The domains for which to obtain a certificate.
         type: list
         elements: str
         required: true
       certbot__http_01_port:
-        description: |
-          The port number the bot listens on. Must be 80 if directly exposed to the internet.
-          Default is 31820 for the public-reverse-proxy setup.
         type: str
         required: false
         default: 31820
       certbot__new_cert_commands:
-        description: >-
-          A list of commands to execute after getting a new certificate.
-          Will be added into a bash script.
         type: list
         elements: str
         required: false