update readme

README.md

@@ -35,6 +35,7 @@ You’ll need the following tools installed:
 - `qemu-system-i386`
 
 Optional:
+
 - `gdb`
 - `vncviewer` (TigerVNC or similar)
 
@@ -42,13 +43,27 @@ Optional:
 
 ## 🛠️ Building ClassicOS
 
-Clone and build:
+Clone repository:
 
-```bash
+```sh
 git clone https://github.com/gbowne1/ClassicOS.git
 cd ClassicOS
-make
 ```
 
-build kernel
-for %f in (*.c) do gcc -m32 -O0 -Wall -Wextra -Werror -pedantic -ffreestanding -nostdlib -fno-pic -fno-stack-protector -fno-pie -march=i386 -mtune=i386 -c "%f" -o "%f.o"
+Run `configure` script to build a cross-compiler toolchain for `i386-elf`:
+
+```sh
+./configure
+```
+
+Source the `.build.env` file to add the cross-compiler toolchain to your PATH:
+
+```sh
+source .build.env
+```
+
+Build the kernel:
+
+```sh
+make
+```