docs(docs/install): remove outdated Apple Silicon ARM64 warning (#24906)

Removes the outdated Apple Silicon ARM64 warning block from the install
docs.

Coder compiles fine for ARM64, and the chip variant list (M1/M2/M3/M4)
would never stay up to date as new chips are released.

Fixes https://linear.app/codercom/issue/DEVREL-19

> Generated with [Coder Agents](https://coder.com/agents)

docs/install/index.md

@@ -27,23 +27,6 @@ curl -L https://coder.com/install.sh | sh
 Refer to [GitHub releases](https://github.com/coder/coder/releases) for
 alternate installation methods (e.g. standalone binaries, system packages).
 
-> [!Warning]
-> If you're using an Apple Silicon Mac with ARM64 architecture, so M1/M2/M3/M4, you'll need to use an external PostgreSQL Database using the following commands:
-
-``` bash
-# Install PostgreSQL
-brew install postgresql@16
-
-# Start PostgreSQL
-brew services start postgresql@16
-
-# Create database
-createdb coder
-
-# Run Coder with external database
-coder server --postgres-url="postgres://$(whoami)@localhost/coder?sslmode=disable"
-```
-
 ## Windows
 
 If you plan to use the built-in PostgreSQL database, ensure that the