docs: Documentation for custom landing directory

INSTALLATION.md

@@ -94,7 +94,10 @@ To enable public mode, set `public_mode` to `Enable`. With this, anyone will be
 links. Listing existing links or deleting links will need admin access using the password. If
 `public_mode` is enabled, and `public_mode_expiry_delay` is set to a positive value, submitted links
 will expire in that given time. The user can still choose a shorter expiry delay.
-To completely disable the frontend, set `disable_frontend` to `True`.
+To completely disable the frontend, set `disable_frontend` to `True`. If you want to serve a custom
+landing page, put all your site related files, along with an `index.html` file in a directory, and
+set `custom_landing_directory` to the path of the directory. If using docker, you need to first
+mount the directory inside the container. The admin page will then be located at `/admin/manage`.
 
 By default, the server sends no Cache-Control headers. You can set custom `cache_control_header` 
 to send your desired headers. It must be a comma separated list of valid 

README.md

@@ -47,6 +47,7 @@ for small. URL means, well... URL. So the name simply means Small URL.
   i.e. only the hit is recorded, and nothing else.
 - Supports operation using API key, and lets the user provide hashed password and API key.
 - Has a mobile friendly UI, and automatic dark mode.
+- Can serve a custom landing page, if needed.
 - Has a public mode, where anyone can add links without authentication. Deleting 
   or listing available links will need admin access using the password. It's also 
   possible to completely disable the frontend. It's also possible to force an expiry 

compose.yaml

@@ -76,6 +76,10 @@ services:
             # In case you want to completely disable the frontend, change the following
             # to True.
             # - disable_frontend=False
+            # If you want to serve a custom landing page, put all your site related files, along with an
+            # index.html file in a directory, and set the following to the path of the directory. Remember to first 
+            # mount the directory inside the container. The admin page will then be located at /admin/manage.
+            # - custom_landing_directory=/custom/dir/location
             
             # By default, the server sends no Cache-Control headers. You can supply a 
             # comma separated list of valid header as per RFC 7234 §5.2 to send those