docs: add PowerShell and Windows install instructions (#3096)

This adds instructions for:

- Installing Atuin on Windows using
[WinGet](https://github.com/microsoft/winget-cli), which is the official
Windows package manager shipped with Windows 11,
- Initializing Atuin in PowerShell by editing its profile file.

It also adds mentions of PowerShell support at the tier 2 level. I hope
this is ok, as we now have a Windows build in the releases and an easy
way to distribute it using a package manager.

Many thanks to @mloskot for [submitting the
manifest](https://github.com/microsoft/winget-pkgs/pull/331328) to the
WinGet community repository. 🚀

Closes #2386

## Checks
- [x] I am happy for maintainers to push small adjustments to this PR,
to speed up the review cycle
- [x] I have checked that there are no existing pull requests for the
same thing

4 files changed, 36 insertions, 0 deletions

diff --git a/docs/docs/guide/dotfiles.md b/docs/docs/guide/dotfiles.md
index 79a571ce..d4157cb7 100644
--- a/docs/docs/guide/dotfiles.md
+++ b/docs/docs/guide/dotfiles.md
@@ -13,6 +13,7 @@ The following shells are supported:
 - bash
 - fish
 - xonsh
+- powershell
 
 Note: Atuin handles your configuration internally, so once it is installed you
 no longer need to edit your config files manually.
diff --git a/docs/docs/guide/getting-started.md b/docs/docs/guide/getting-started.md
index c25645d0..85140b25 100644
--- a/docs/docs/guide/getting-started.md
+++ b/docs/docs/guide/getting-started.md
@@ -20,6 +20,7 @@ If you have any problems, please open an [issue](https://github.com/ellie/atuin/
 - fish
 - nushell
 - xonsh
+- powershell (tier 2 support)
 
 ## Quickstart
 
diff --git a/docs/docs/guide/installation.md b/docs/docs/guide/installation.md
index 72130af4..aeb33518 100644
--- a/docs/docs/guide/installation.md
+++ b/docs/docs/guide/installation.md
@@ -2,6 +2,8 @@
 
 ## Recommended installation approach
 
+### On Unix
+
 Let's get started! First up, you will want to install Atuin. The recommended
 approach is to use the installation script, which automatically handles the
 installation of Atuin including the requirements for your environment.
@@ -16,6 +18,21 @@ curl --proto '=https' --tlsv1.2 -LsSf https://setup.atuin.sh | sh
 
 [**Set up sync** - Move on to the next step, or read on to manually install Atuin instead.](sync.md)
 
+### On Windows
+
+The recommended approach on Windows is to use WinGet to install Atuin. Then, if you use PowerShell,
+add the initialization command to your PowerShell profile, and restart your shell.
+
+```shell
+winget install -e Atuinsh.Atuin
+if (-not (Test-Path -Path $PROFILE)) { New-Item -ItemType File -Path $PROFILE -Force | Out-Null }
+Write-Output 'atuin init powershell | Out-String | Invoke-Expression' >> $PROFILE
+```
+
+Note that the `$PROFILE` path may depend on your PowerShell version.
+
+[**Set up sync** - Move on to the next step.](sync.md)
+
 ## Manual installation
 
 ### Installing the binary
@@ -105,6 +122,14 @@ If you don't wish to use the installer, the manual installation steps are as fol
     zinit light atuinsh/atuin
     ```
 
+=== "WinGet"
+
+    Atuin is available on WinGet:
+
+    ```shell
+    winget install -e Atuinsh.Atuin
+    ```
+
 === "Source"
 
     Atuin builds on the latest stable version of Rust, and we make no
@@ -232,6 +257,14 @@ After installing, remember to restart your shell.
     ```
     to the end of your `~/.xonshrc`
 
+=== "PowerShell"
+
+    Add the following to the end of your `$PROFILE` file:
+
+    ```shell
+    atuin init powershell | Out-String | Invoke-Expression
+    ```
+
 ## Upgrade
 
 Run `atuin update`, and if that command is not available, run the install script again.
diff --git a/docs/docs/index.md b/docs/docs/index.md
index 76a4b51f..43ef2f9c 100644
--- a/docs/docs/index.md
+++ b/docs/docs/index.md
@@ -22,6 +22,7 @@ Alternatively, get in touch on our [Discord](https://discord.gg/Fq8bJSKPHh) or o
 - fish
 - nushell
 - xonsh
+- powershell (tier 2 support)
 
 ## Quickstart