docs(Readme.md): Update Readme

Update the readme to better match the current state of the project.

Readme.md

@@ -1,22 +1,95 @@
 # CsSiteGen
 A relatively simple (for now) static site "generator".
-The heavy lifting of this project is actually performed by `Pandoc` so you
+The heavy lifting of this project is actually performed by `pandoc` so you
 better make sure you install it on your system.
 
 ## How to use
-This project is nowhere near a finished thing so I wouldn't recommend
-relying it on it at the moment.
+The configuration for a site is stored in a file called `cssitegen.json`
+this file can technically be located anywhere but the recommended directory
+structure is as follows:
+```
+-Project-Root
+ |
+ |-Source_Directory
+ | |
+ | |- [source files...]
+ |
+ |-Destination_Directory
+ |
+ |-cssitegen.json
+```
+This makes the file much simpler to write, However with fully specified
+paths you can actually place the files anywhere.
 
-But the general method of operation (for the moment) is to run it like
-this:
-```sh
-cssitegen convert [INPUT_DIRECTORY] [OUTPUT_DIRECTORY]
+### Structure of `cssitegen.json`
+All `cssitegen.json` files must specify at minimum the source, and
+destination directories, If the baseurl is omitted it will simply be null.
+You must also ensure that you follow the JSON format properly.
+The following fields are used in a file
+- Source - a string that locates the source files. This can either be the
+full path or a relative path.
+- Destination - As above but this is where the output files will go.
+- BaseUrl - a string or `null` this will be used to replace the string
+`%BASEURL%` in supported files. (Depending on your usage you may need to
+specify the protocol)
+
+#### Example file
+```json
+{
+    "Source" : "./Source",
+    "Destination" : "./Destination",
+    "BaseUrl" : "https://example.org"
+}
 ```
 
-At the moment the basic Markdown to HTML conversion is implemented, but
-future plans include automatic conversion of images to `webp` and other
-optimisations.
+### Executing the program
+Currently the program has two subcommands that can be used, and an optional
+project argument, if not specified the program assumes that the project is
+the current directory.
+
+The program is called like this
+```sh
+cssitegen SUBCOMMAND [--project "directory"]
+```
+#### convert
+This subcommand performs conversion of the files.
+It only considers source files for conversion if they are new or have been
+changed since the last run of the program.
+Therefore if you change the `BaseUrl` or the template file you will need to
+clean and convert your entire project.
+Convert also does not detect deleted source files at the moment, so you
+will also need to clean for that,
+
+#### clean
+This subcommand purges the output directory, You can of course do this
+manually but for convenience this is implemented here.
+
+### Templating
+The templating system is managed by `pandoc` so please check the
+documentation for `pandoc` to learn about the format.
+
+As for where to place the template files,
+for every file converted using `pandoc` the program will attempt to locate
+the appropriate template named as `.template`, it first looks in the
+directory of the source file, and then works its way up the directory tree
+until it hits the root directory, using the first template it finds.
+This means that if you want different templates for some sections of your
+site you can do that, and other sections will fallback to your root
+template.
+_If you don't specify a template you will get the `pandoc` defaults_
+
+### BaseUre replacement
+Currently the string `%BASEURL%` will be replaced in `.md` `.html` and
+template files. This feature is something you will definitely want to use,
+unless you want to structure everything to the point you only need relative
+links. (I personally found this almost impossible)
 
 ## Future plans
-Automatic page generation using pre-process steps and temporary files.
-E.G Contents pages, index pages etc...
+- Automatic page generation using pre-process steps and temporary files.
+E.G Contents pages, index pages etc...(DIFFICULT)
+- Detection of changes to the `BaseUrl` and any templates. (MEDIUM)
+- Detection of deleted source files and removal of the destination
+files.(MEDIUM)
+- Allow expansion of conversion operations (DIFFICULT)
+- Allow customisation of filetypes that can have `%BASEURL%` replaced
+(EASY-MEDIUM)