docs: linter & packagers guide & chores (#64)

add prettier, move most markdown into `docs/` and add a packagers guide

---

* lint(md): add prettier

* docs(packagers): add a guide

* docs(correctness): Index -> ToC

* docs: link to package maintainers guide

* docs: move install docs to `./docs`

* docs(fix): typo

docs/INSTALL.md

@@ -0,0 +1,128 @@
+# Table of Contents
+
+- [Installing from Source](#installing-from-source)
+- [AUR](#aur)
+- [Nix Flake](#nix-flake)
+- [Nix Module](#nix-module)
+
+> [!CAUTION]
+> I encourage you to read the manual installation steps to understand what will get installed in your computer by this package.
+
+# Installing from Source
+
+Firstly, you'll need to build the package, this also includes man pages, default config, themes and other files you might need.
+
+To build it you only need to have some basic packages (should come pre-installed in almost all distros): `make`, `gcc` or another `gcc`ish compiler, and libpam headers. If it builds, it surely works anyways.
+
+```sh
+git clone https://github.com/javalsai/lidm.git
+cd lidm
+make # 👍
+```
+
+> [!NOTE]
+> There's pre-built binaries on the [releases tab](https://github.com/javalsai/lidm/releases) too.
+
+Then you can install the files onto your filesystem with:
+
+```sh
+make install
+```
+
+And additionally, to install service files (start-up behavior). <sup>[more docs](./assets/services/README.md)</sup>
+
+```sh
+# automatically detects your init system
+# and install service file (for tty7)
+make install-service
+
+# or if you don't like autodetection
+make install-service-systemd # systemd
+make install-service-dinit # dinit
+make install-service-runit # runit (/etc/sv)
+make install-service-runit-etc # runit (/etc/runit/sv)
+make install-service-openrc # openrc
+make install-service-s6 # s6 (/etc/sv)
+make install-service-s6-etc # s6 (/etc/s6/sv)
+
+#  For runit and s6, some distros (e.g. Artix) like to put it in /etc/<init>/sv
+# to better isolate their packages while other distros (e.g. Void) just put it
+# in /etc/sv
+```
+
+# AUR
+
+[AUR packages](https://aur.archlinux.org/packages?K=lidm&SeB=n) will automatically install most files.
+
+> [!CAUTION]
+> [service files](./assets/pkg/aur#services) have to be manually installed by now.
+
+# Nix Flake
+
+You can install by doing
+
+```sh
+nix profile install github:javalsai/lidm
+```
+
+or try it out without installing by:
+
+```sh
+nix run github:javalsai/lidm
+```
+
+> [!CAUTION]
+> This doesn't include [service files](./assets/pkg/aur#services) neither
+
+# Nix Module
+
+<details>
+<summary>Sidenote</summary>
+
+The nix module lacks on several aspects, if you know much about nix and know
+how to improve this package, feel free to open an issue or a PR to help. The
+nix package maintainer position is open too.
+
+</details>
+
+Lidm includes a nix module in `assets/pkg/nix/module.nix` that you can add
+(along the included nix files) and import in your `configuration.nix`.
+
+Once imported you'll need to add:
+
+```nix
+services.displayManager.enable = true;
+systemd.services.lidm.enable = true;
+```
+
+Optionally, you can configure it setting `services.lidm.config`. You can either
+pass:
+
+- A string to copy the config from a theme in `themes/` with said name
+  (**name**, e.g `"cherry"`).
+- An attribute tree with the same names as the config file, e.g:
+
+```nix
+with config.lidm.keysEnum; {
+    strings = {
+        f_poweroff = "custom_poweroff";
+    };
+
+    behavior = {
+        include_defshell = true;
+        source = [
+            "path1"
+            "path2"
+        ];
+    };
+
+    functions = { poweroff = F1; };
+
+    # etc...
+};
+```
+
+> _it's not necessary to cover all keys and anything can be put there, even if it's not valid config_
+
+> [!NOTE]
+> [service files](./assets/pkg/aur#services) **are** included and enabled