[llvm] [llvm][Docs] Update guide to include ``pip install lit`` (PR #106526)

[via llvm-commits]

https://github.com/MichelleCDjunaidi created https://github.com/llvm/llvm-project/pull/106526

Also updates and clarifies which version would be installed.

As per https://discourse.llvm.org/t/information-on-lit-is-outdated/76498/10?u=mch_dj7.

>From b30a63b0b94e8e8d19e3b051336c87421ed8433b Mon Sep 17 00:00:00 2001
From: MichelleCDjunaidi <87893361+MichelleCDjunaidi at users.noreply.github.com>
Date: Thu, 29 Aug 2024 18:38:39 +0800
Subject: [PATCH 1/2] Update guide to include ``pip install lit``

Also updates the versions on the guide.
---
 llvm/docs/TestSuiteGuide.md | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/llvm/docs/TestSuiteGuide.md b/llvm/docs/TestSuiteGuide.md
index 9552cd89aa1c1b..2171622dee6c0a 100644
--- a/llvm/docs/TestSuiteGuide.md
+++ b/llvm/docs/TestSuiteGuide.md
@@ -9,10 +9,10 @@ Quickstart
 
    ```bash
    % <path to llvm build>/bin/llvm-lit --version
-   lit 0.8.0dev
+   lit 20.0.0dev
    ```
 
-   An alternative is installing it as a python package in a python virtual
+   An alternative is installing it as a Python package in a python virtual
    environment:
 
    ```bash
@@ -20,7 +20,17 @@ Quickstart
    % . .venv/bin/activate
    % pip install git+https://github.com/llvm/llvm-project.git#subdirectory=llvm/utils/lit
    % lit --version
-   lit 0.8.0dev
+   lit 20.0.0dev
+   ```
+
+   Installing the official Python release of lit in a Python virtual
+   environment would also work.
+   ```bash
+   % python3 -m venv .venv
+   % . .venv/bin/activate
+   % pip install lit
+   % lit --version
+   lit 18.1.8
    ```
 
 2. Check out the `test-suite` module with:

>From f06da8caebee7435a33393c42086c739d7e4c6ab Mon Sep 17 00:00:00 2001
From: MichelleCDjunaidi <87893361+MichelleCDjunaidi at users.noreply.github.com>
Date: Thu, 29 Aug 2024 18:42:11 +0800
Subject: [PATCH 2/2] Clarify version installed by lit

---
 llvm/docs/TestSuiteGuide.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/docs/TestSuiteGuide.md b/llvm/docs/TestSuiteGuide.md
index 2171622dee6c0a..0a02c570328781 100644
--- a/llvm/docs/TestSuiteGuide.md
+++ b/llvm/docs/TestSuiteGuide.md
@@ -24,7 +24,8 @@ Quickstart
    ```
 
    Installing the official Python release of lit in a Python virtual
-   environment would also work.
+   environment would also work. This will install the most recent 
+   release of lit:
    ```bash
    % python3 -m venv .venv
    % . .venv/bin/activate