jeff merge (#308)

* docs: add examples, getting started, install, reference guide

* fix file endings with dos2unix

* refs: add syntax on fence quotes

* refs: move repo to numtide

* docs: remove WIP notes and fix outdated link

- Remove author WIP/TODO notes from examples.md, install.md, reference-guide.md
- Update documentation link in faq.md to point to docs/ instead of manual/

* docs: fix broken anchor links

- Fix heading typo "Exapmle" -> "Example" for HTTPS nginx section
- Remove TOC entries for sections that don't exist in reference-guide.md
- Fix cross-page link in install.md to reference-guide.md
- Remove stale "FAQ" TODO note from TOC

* docs: add nav section to control page ordering

* docs: add homepage introduction

* docs: fix Example 1 timer system.nix code block

* docs: add rollback limitation warning

* Revert "docs: add homepage introduction"

This reverts commit 05bdd9c.

* docs: add introduction page

* docs: rename install.md to requirements.md, remove duplicate content

* docs: standardize System Manager capitalization in prose

* docs: add inline code formatting for paths, commands, and attributes

Apply backticks to:
- File paths (/etc/nix/nix.conf, ~/.config/system-manager, etc.)
- File names (flake.nix, system.nix, .nix files)
- Package names (bat, tree, hello, etc.)
- Nix attributes (systemPackages, wantedBy, config, etc.)
- Commands and options (--sudo, --flake, init, switch, etc.)
- Environment variables (PATH, $PATH)

Also fix several typos: "bulit-in" -> "built-in", "imputs" -> "inputs",
"sipmly" -> "simply", "inluding" -> "including", "ngnix" -> "nginx",
"have to" -> "having to", and fix /opt/nix/nix.conf to /etc/nix/nix.conf.

* docs: improve requirements.md clarity and structure

- Remove redundant admonitions that repeated bullet list items
- Rename "Installation" to "No Installation Required" for clarity
- Add first-run example command with link to getting-started.md
- Rename "Regarding Experimental Features" to "Enabling Flakes"
- Simplify experimental features section, link to reference-guide.md
- Add language identifiers to code blocks (ini, sh, console)
- Fix awkward phrasing ("installed off of" -> "installed in")
- Remove extra blank lines

* docs: rename requirements.md to install.md, focus on installation

- Rename page from "System Requirements" to "Installation"
- Add "Installing Nix" section with official multi-user installer
- Add "Enabling Flakes" section (required after official install)
- Link to nix-install.com for alternative installation options
- Add "Checking Your Installation" section for system-wide verification
- Update nav and all links to use install.md

* docs: move --sudo explanation from install.md to getting-started.md

The --sudo flag is about running System Manager, not installing it.
Move the explanation to where users first encounter the switch command,
with a clearer description of what it does.

* misc

* docs: consolidate experimental features documentation into install.md

Remove duplicate explanations of Nix flakes/experimental features from
getting-started.md and reference-guide.md. These now reference the
canonical "Enabling Flakes" section in install.md.

* docs: split reference-guide.md into modular reference/ directory

Reorganize the monolithic reference-guide.md (~2000 lines) into a
structured reference/ subdirectory with focused files:

- reference/index.md: Overview linking to all sections
- reference/cli.md: CLI commands and local installation
- reference/configuration.md: Project setup and workflows
- reference/modules.md: Services, packages, /etc, tmpfiles
- reference/remote-flakes.md: Remote flake hosting
- reference/blueprint.md: Blueprint integration
- reference/examples/: Individual example files (timer, docker,
  postgresql, nginx, nginx-https, custom-app)

Also migrates examples from examples.md into the new structure and
updates all cross-references.

* docs: complete 'Running System Manager with a remote flake' section

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Co-authored-by: Jeffrey Freckleface Cogswell <[email protected]>