Add document BlockParametersNode fields

Partially fixes: #2123

config.yml

@@ -1172,13 +1172,49 @@ nodes:
       - name: parameters
         type: node?
         kind: ParametersNode
+        comment: |
+          Represents the parameters of the block.
+
+              -> (a, b = 1; local) { }
+                  ^^^^^^^^
+
+              foo do |a, b = 1; local|
+                      ^^^^^^^^
+              end
       - name: locals
         type: node[]
         kind: BlockLocalVariableNode
+        comment: |
+          Represents the local variables of the block.
+
+              -> (a, b = 1; local) { }
+                            ^^^^^
+
+              foo do |a, b = 1; local|
+                                ^^^^^
+              end
       - name: opening_loc
         type: location?
+        comment: |
+          Represents the opening location of the block parameters.
+
+              -> (a, b = 1; local) { }
+                 ^
+
+              foo do |a, b = 1; local|
+                     ^
+              end
       - name: closing_loc
         type: location?
+        comment: |
+          Represents the closing location of the block parameters.
+
+              -> (a, b = 1; local) { }
+                                 ^
+
+              foo do |a, b = 1; local|
+                                     ^
+              end
     comment: |
       Represents a block's parameters declaration.