[RFC] Add back original Triton setup instructions (#1693)

Fixes: #1692

Avoid diverging setup instructions vs. upstream Triton. Add
clarification on `.triton` cache folder. Add a note about
`compile-triton.sh` script.

Signed-off-by: Dmitry Rogozhkin <[email protected]>

README.md

@@ -20,19 +20,28 @@ This is the development repository of Intel® XPU Backend for Triton\*, a new [T
 # Install from source
 
 ```
-git clone https://github.com/intel/intel-xpu-backend-for-triton.git -b llvm-target
-cd intel-xpu-backend-for-triton
-scripts/compile-triton.sh
+git clone https://github.com/intel/intel-xpu-backend-for-triton.git;
+cd intel-xpu-backend-for-triton;
+
+pip install ninja cmake wheel; # build-time dependencies
+pip install -e python
 ```
 
 Or with a virtualenv:
 
 ```
-git clone https://github.com/intel/intel-xpu-backend-for-triton.git -b llvm-target
-cd intel-xpu-backend-for-triton
-scripts/compile-triton.sh --venv
+git clone https://github.com/intel/intel-xpu-backend-for-triton.git;
+cd intel-xpu-backend-for-triton;
+
+python -m venv .venv --prompt triton;
+source .venv/bin/activate;
+
+pip install ninja cmake wheel; # build-time dependencies
+pip install -e python
 ```
 
+Note that `$HOME/.triton` folder is used as default cache location at build time. Developers might find `scripts/compile-triton.sh` script useful for advanced build options.
+
 # Building with a custom LLVM
 
 Triton uses LLVM to generate code for GPUs and CPUs.  Normally, the Triton build