Add support for maintainer instruction

corpus/maintainer.txt

@@ -0,0 +1,10 @@
+==================
+Simple
+==================
+
+Maintainer camden@ccheek.com
+
+---
+
+(source_file
+	(maintainer_instruction))

grammar.js

@@ -24,6 +24,7 @@ module.exports = grammar({
 						$.stopsignal_instruction,
 						$.healthcheck_instruction,
 						$.shell_instruction,
+						$.maintainer_instruction,
 				),
 
 				from_instruction: $ => seq(
@@ -183,6 +184,11 @@ module.exports = grammar({
 						$._non_newline_whitespace,
 						$.string_array,
 				),
+
+				maintainer_instruction: $ => seq(
+						alias(/[mM][aA][iI][nN][tT][aA][iI][nN][eE][rR]/, "MAINTAINER"),
+						/.*/,
+				),
 				
 				path: $ => seq(
 					choice(

src/grammar.json

@@ -87,6 +87,10 @@
         {
           "type": "SYMBOL",
           "name": "shell_instruction"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "maintainer_instruction"
         }
       ]
     },
@@ -770,6 +774,24 @@
         }
       ]
     },
+    "maintainer_instruction": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "ALIAS",
+          "content": {
+            "type": "PATTERN",
+            "value": "[mM][aA][iI][nN][tT][aA][iI][nN][eE][rR]"
+          },
+          "named": false,
+          "value": "MAINTAINER"
+        },
+        {
+          "type": "PATTERN",
+          "value": ".*"
+        }
+      ]
+    },
     "path": {
       "type": "SEQ",
       "members": [

src/node-types.json

@@ -409,6 +409,11 @@
       }
     }
   },
+  {
+    "type": "maintainer_instruction",
+    "named": true,
+    "fields": {}
+  },
   {
     "type": "onbuild_instruction",
     "named": true,
@@ -457,6 +462,10 @@
           "type": "label_instruction",
           "named": true
         },
+        {
+          "type": "maintainer_instruction",
+          "named": true
+        },
         {
           "type": "onbuild_instruction",
           "named": true
@@ -618,6 +627,10 @@
           "type": "label_instruction",
           "named": true
         },
+        {
+          "type": "maintainer_instruction",
+          "named": true
+        },
         {
           "type": "onbuild_instruction",
           "named": true
@@ -842,6 +855,10 @@
     "type": "LABEL",
     "named": false
   },
+  {
+    "type": "MAINTAINER",
+    "named": false
+  },
   {
     "type": "NONE",
     "named": false