docs: Use plain quotes for callouts (#9499)

This PR adjusts our docs to use plain Markdown quotes for callouts.

This Markdown gets rendered in a number of different locations:

- GitHub
- zed.dev
- mdBook

As such, we should use Markdown that is supported by all three.

Release Notes:

- N/A

docs/src/SUMMARY.md

@@ -1,6 +1,7 @@
 # Summary
 
 [Getting Started](./getting_started.md)
+  - [System Requirements](./system_requirements.md)
 [Feedback](./feedback.md)
 
 # Configuring Zed

docs/src/languages/elixir.md

@@ -19,9 +19,7 @@ brew install elixir-ls
 
 3. Restart Zed
 
-{% hint style="warning" %}
-If `elixir-ls` is not running in an elixir project, check the error log via the command palette action `zed: open log`. If you find an error message mentioning: `invalid LSP message header "Shall I install Hex? (if running non-interactively, use \"mix local.hex --force\") [Yn]`, you might need to install [`Hex`](https://hex.pm). You run `elixir-ls` from the command line and accept the prompt to install `Hex`.
-{% endhint %}
+> If `elixir-ls` is not running in an elixir project, check the error log via the command palette action `zed: open log`. If you find an error message mentioning: `invalid LSP message header "Shall I install Hex? (if running non-interactively, use \"mix local.hex --force\") [Yn]`, you might need to install [`Hex`](https://hex.pm). You run `elixir-ls` from the command line and accept the prompt to install `Hex`.
 
 ### Formatting with Mix
 

docs/src/system_requirements.md

@@ -4,9 +4,7 @@
 
 Supported versions: Catalina (10.15) - Sonoma (14.x).
 
-{% hint style="info" %}
-The implementation of our screen sharing feature makes use of [LiveKit](https://livekit.io). The LiveKit SDK requires macOS Catalina (10.15); consequently, in v0.62.4, we dropped support for earlier macOS versions that we were initially supporting.
-{% endhint %}
+> The implementation of our screen sharing feature makes use of [LiveKit](https://livekit.io). The LiveKit SDK requires macOS Catalina (10.15); consequently, in v0.62.4, we dropped support for earlier macOS versions that we were initially supporting.
 
 ## Linux, Windows, and Web
 

docs/src/tasks.md

@@ -0,0 +1 @@
+# Tasks