readme: Remove command to fetch latest version

From @LordMZTE:

> if you delete the package from the zig cache and then try building, you
> will get a hash mismatch.
>
> the hash is derived from the contents of the dependency and it must
> match or you get an error. a condition for this to work is that the
> specified url always returns the same thing, which isn't the case for a
> branch (when you push something).
>
> you might've gotten the feeling that this works because when zig finds
> the hash you specified in it's cache, it will not check the URL to see
> if it matches.

README.md

@@ -20,10 +20,6 @@ _Getty JSON_ is a (de)serialization library for the JSON data format.
 1. Declare Getty JSON as a project dependency with `zig fetch`:
 
     ```sh
-    # Latest version
-    zig fetch --save git+https://github.com/getty-zig/json.git#main
-
-    # Specific version
     zig fetch --save git+https://github.com/getty-zig/json.git#<COMMIT>
     ```