chore: README.md update of breaking changes in langauges.ncl

Author: blindFS

README.md

@@ -9,14 +9,31 @@
 
 ## setup
 
-1. install latest topiary-cli
+1. install topiary-cli (0.5.1 above)
 2. clone this repo to `$env.XDG_CONFIG_HOME/topiary`
 3. set environment variables
 ```nu
 $env.TOPIARY_CONFIG_FILE = ($env.XDG_CONFIG_HOME | path join topiary languages.ncl)
 $env.TOPIARY_LANGUAGE_DIR = ($env.XDG_CONFIG_HOME | path join topiary languages)
 ```
+4. update `languages.ncl` if Nickel error detected: `grammar.source.git` fits recent updates of topiary github
+while the latest release of topiary-cli still uses the other way.
+
+```diff
+<       grammar = {
+---
+>       grammar.source.git = {
+```
 
 ## usage
 
 `topiary format script.nu`
+
+## contribute
+
+Help to find format issues with following method (dry-run, detects parsing/idempotence/semantic breaking):
+
+```nu
+source utils.nu
+test_format <root-path-of-your-nushell-scripts>
+```

utils.nu

@@ -30,5 +30,6 @@ export def test_format [
         break
       }
     }
+    rm $target
   }
 }