readme: Updates (#51)

* Replace the EVM version with the latest

(also, explain how to get it)

* Separate install, test generation

* Update README.md

* Update README.md

* Update README.md

---------

Co-authored-by: Mario Vega <[email protected]>

Author: qbzzt

README.md

@@ -1,7 +1,6 @@
 # Execution Spec Tests
 
-This repository provides tools and libraries for generating cross-client
-Ethereum tests.
+This repository provides tools and libraries for generating cross-client Ethereum tests.
 
 ## Quick Start
 
@@ -10,10 +9,17 @@ Ethereum tests.
 The following are required to either generate or develop tests:
 
 1. Python `3.10.0`.
-2. [`go-ethereum`](https://github.com/ethereum/go-ethereum) `v1.10.13` for `geth`'s `evm` utility which must be accessible in the `PATH`. See https://github.com/ethereum/go-ethereum#building-the-source for information on how to build go-ethereum utilities.
+2. [`go-ethereum`](https://github.com/ethereum/go-ethereum) `geth`'s `evm` utility must be accessible in the `PATH`, typically at the latest version. To get it:
+   1. Install [the Go programming language](https://go.dev/doc/install) on your computer.
+   2. Clone [the Geth repository](https://github.com/ethereum/go-ethereum).
+   3. Run `make all`.
+   4. Copy `build/bin/evm` to a directory on the path.
+   
+   **Note:** To update to a different Geth branch (for example one that supports a specific EIP) all you need to do is to change the `evm` in the path.
+   
 3. [`solc`](https://github.com/ethereum/solidity) >= `v0.8.17`; `solc` must be in accessible in the `PATH`.
 
-### Generating the Execution Spec Tests For Use With Clients
+### Installation
 
 To generate tests from the test "fillers", it's necessary to install the Python packages provided by `execution-spec-tests` (it's recommended to use a virtual environment for the installation):
 
@@ -25,6 +31,17 @@ source ./venv/bin/activate
 pip install -e .
 ```
 
+After the installation, run this sanity check to ensure tests are generated.
+If everything is OK, you will see the beginning of the JSON format filled test.
+
+```console
+tf --output="fixtures" --test-case yul
+head fixtures/example/example/yul.json
+```
+
+
+### Generating the Execution Spec Tests For Use With Clients
+
 To generate all the tests defined in the `./fillers` sub-directory, run the `tf` command:
 
 ```console
@@ -59,6 +76,7 @@ pip install tox
 tox -e py3
 ```
 
+
 ## Execution Spec Tests Package Overview 
 
 ### `ethereum_test_tools`