Add nilinit option descriptor

Rules.md

@@ -1739,7 +1739,7 @@ Remove/insert redundant `nil` default value (Optional vars are nil by default).
 
 Option | Description
 --- | ---
-`--nilinit` | Explicit self: "insert", "remove" (default)
+`--nilinit` | "remove" (default) redundant nil or "insert" missing nil
 
 <details>
 <summary>Examples</summary>

Sources/Examples.swift

@@ -564,17 +564,17 @@ private struct Examples {
     let foo: Int? = nil
     ```
 
+    ```diff
+    // doesn't affect non-nil initialization
+    var foo: Int? = 0
+    ```
+
     `--nilinit insert`
 
     ```diff
     - var foo: Int?
     + var foo: Int? = nil
     ```
-
-    ```diff
-    // doesn't affect non-nil initialization
-    var foo: Int? = 0
-    ```
     """
 
     let redundantObjc = """

Sources/OptionDescriptor.swift

@@ -1027,6 +1027,12 @@ struct _Descriptors {
         fromArgument: { FormatTimeZone(rawValue: $0) },
         toArgument: { $0.rawValue }
     )
+    let nilInitType = OptionDescriptor(
+        argumentName: "nilinit",
+        displayName: "Nil init type",
+        help: "\"remove\" (default) redundant nil or \"insert\" missing nil",
+        keyPath: \.nilInitType
+    )
 
     // MARK: - Internal