Merge 'docs: fix CLI command and add homebrew install instructions for MacOS' from Mattia

Hi there,
I wasn't able to run the Turso CLI locally following the manual in the
docs (with both the release version and Homebrew). I found out that the
right command is `tursodb` rather than just turso as specified in the
cli/Cargo.toml.
This MR updates the docs and also mention the instruction to install it
with Homebrew.
Demo:
<img width="629" height="129" alt="image" src="https://github.com/user-
attachments/assets/3c684328-dab6-436a-bae6-4b6199f5b0b5" />

Reviewed-by: Preston Thorpe <preston@turso.tech>

Closes #2514

docs/manual.md

@@ -52,10 +52,16 @@ curl --proto '=https' --tlsv1.2 -LsSf \
   https://github.com/tursodatabase/turso/releases/latest/download/turso_cli-installer.sh | sh
 ```
 
+Or alternatively, on MacOS, you can use Homebrew:
+
+```
+brew install turso
+```
+
 When you have the software installed, you can start a SQL shell as follows:
 
 ```console
-$ turso
+$ tursodb
 Turso
 Enter ".help" for usage hints.
 Connected to a transient in-memory database.