Added a README.md for the CLI

src/Itofinity.Appveyor.Cli/README.md

@@ -0,0 +1,86 @@
+## Install
+Download the latest release for your platform from https://github.com/itofinity/Itofinity-Appveyor-Refit/releases.
+
+Currently releases for all platforms are in the form of self-contained zips, simply extract the contents to a folder of your choice.
+
+There are _no_ external dependencies.
+
+## Run
+
+### Windows
+
+    >\path\to\install\Itofinity.Appveyor.Cli.exe
+
+### Linux
+
+    >\path\to\install\Itofinity.Appveyor.Cli
+
+### macOS
+
+    >\path\to\install\Itofinity.Appveyor.Cli
+
+Documentation for now refers to the windows .exe version, but it should be simple to adjust.
+
+## Options
+
+The cli is built to be self-explanatory but, its early days, so here are some basics
+
+To access a list of available commands
+
+    >Itofinity.Appveyor.Cli.exe --help
+
+To access help on a specific command
+
+    >Itofinity.Appveyor.Cli.exe {command} --help
+
+To run a specific command
+
+    >Itofinity.Appveyor.Cli.exe {command} -t {apikey} --indent
+
+## Commands
+
+### Porcelain Commands
+
+Porcelain commands are auto-generated from the API client, and return JSON.
+
+Porcelain commands are always available
+
+### Extension Commands
+
+Extension commands potentially provide more nuanced parameters and results, since they can be written to achieve a particular task.
+
+Extension commands are loaded by MEF from the _extensions_ sub-folder.
+
+They are not available if the _extensions_ sub-folder is empty.
+
+_Itofinity.AppVeyor.Cli.Ext_ provides some example extension commands.
+
+### Authentication
+
+The AppVeyor API requires authentication, you need an API Key from https://ci.appveyor.com/api-keys, one that is suitable for the account you are trying to access.
+
+You can provide the key specifically via the token parameter 
+
+    >Itofinity.Appveyor.Cli.exe {command} -t {apikey}
+
+Or predefine it as an environment variable
+
+    >$env:APPVEYOR_API_TOKEN={apikey}
+    >Itofinity.Appveyor.Cli.exe {command}
+
+### Common options
+
+    --indent
+
+Json output is raw and un-formattted by default, --indent creates formatted output
+
+    --output
+
+Output is to the calling console by default, --output redirects to the specified file
+
+
+    --filter
+
+Use _jsonpath_ to extract and output only sub-sections, values etc from the main Json response
+
+