docs(mcl): command usage in README

Author: monyarm

README.md

@@ -12,3 +12,87 @@ jobs:
     uses: metacraft-labs/nixos-modules/.github/workflows/ci.yml@main
     secrets: inherit
 ```
+
+## MCL command
+
+The mcl tool contained in this repository has a number of commands which can be given to it as a commandline argument. They are:
+
+### ci_matrix
+
+Evaluates each package, and compares it to it's last cached version, creating a table listing which packages are cached, which aren't, and which failed.
+This command is not meant to be run manually, but rather to be ran by the CI.
+
+ENV Variables:
+- IS_INITIAL: `true` or `false`
+- CACHIX_CACHE: Which cachix cache to search
+- CACHIX_AUTH_TOKEN: The auth token for the cache
+- FLAKE_PRE: Flake path prefix
+- FLAKE_POST: Flake path postfix
+
+Usage: Use `mcl ci` instead
+
+### ci
+
+Evaluates each package, and compares it to it's last cached version, creating a table listing which packages are cached, which aren't, and which failed.
+
+ENV Variables:
+- IS_INITIAL: `true` or `false`
+- CACHIX_CACHE: Which cachix cache to search
+- CACHIX_AUTH_TOKEN: The auth token for the cache
+- FLAKE_PRE: Flake path prefix
+- FLAKE_POST: Flake path postfix
+
+Usage: `mcl ci`
+
+### deploy_spec
+
+Deploys machine specs to cachix.
+
+Usage: `mcl deploy_spec`
+
+### get_fstab
+
+ENV Variables:
+- IS_INITIAL: `true` or `false`
+- CACHIX_CACHE: Which cachix cache to search
+- CACHIX_AUTH_TOKEN: The auth token for the cache
+- [Optional] CACHIX_STORE_URL: URL for the cachix store
+- [Optional] CACHIX_DEPLOY_WORKSPACE: Workspace for cachix deploy (defaults to CACHIX_CACHE if not set)
+- MACHINE_NAME: Which machine to serach
+- DEPLOYMENT_ID: Id of cachix deployment
+
+Usage: `mcl get_fstab`
+
+### host_info
+
+Returns system information, software (OS, Bios) and hardware (CPU, GPU, Ram, MB, Disks) as json.
+
+Usage: `mcl host_info`
+
+### machine_create
+
+Create a starting nix configuration for target machine.
+
+ENV Variables:
+- SSH_PATH: SSH path of target machine
+
+The remaining ENV variables are optional, and if missing will be prompted at runtime.
+- CREATE_USER: bool
+- USER_NAME: string
+- MACHINE_NAME: string
+- DESCRIPTION: string
+- IS_NORMAL_USER: bool
+- EXTRA_GROUPS: comma-delimited list of additional groups to add to the created user
+- MACHINE_TYPE: enum (desktop, server, container)
+- DISKS: comma-delimited list of device names (as per /dev) to add to the nix configuration
+
+Usage: `mcl machine_create`
+
+### shard_matrix
+
+Splits the list of packages under `checks` into n number of shards. Requires manual configuration using modules/shard-split. See this repo and `nix-blockchain-development`
+
+ENV Variables:
+- [Optional] GITHUB_OUTPUT: If set, exports results to GITHUB_INPUT env variable
+
+Usage: `mcl shard_matrix`