Update README.md

Author: p-x9

README.md

@@ -1,3 +1,31 @@
 # RunScriptPlugin
 
-A description of this package.
+SwiftPackage Plugin for executing arbitrary ShellScript.
+
+
+## Usage
+Place the file named `.runscript.yml` in the root of the project.
+Write the shell script you want to run in this file.
+
+The format is as follows.
+
+```yaml
+prebuild: # prebuildCommand
+  - name: "Hello"
+    script: "echo Hello" # Write scripts directly
+  - name: "Show current path"
+    script: "pwd"
+  - name: "Write file"
+    script: "echo Hello >> test.txt"
+  - name: "SwiftLint"
+    launchPath: "/bin/bash" # bash, zsh, etc. can be specified
+    script: "swiftlint lint --fix"
+
+  - name: "Update schema"
+    file: "update_schema.sh" # Execute .sh file
+
+build: # build Command
+   - name: "Hello"
+     script: "echo Hello"
+
+```