Add document BlockParameterNode fields

Partially fixes: #2123

Author: ydah

config.yml

@@ -1157,10 +1157,27 @@ nodes:
  fields:
  - name: name
  type: constant?
+ comment: |
+ The name of the block parameter.
+
+ def a(&b) # name `:b`
+ ^
+ end
  - name: name_loc
  type: location?
+ comment: |
+ Represents the location of the block parameter name.
+
+ def a(&b)
+ ^
  - name: operator_loc
  type: location
+ comment: |
+ Represents the location of the `&` operator.
+
+ def a(&b)
+ ^
+ end
  comment: |
  Represents a block parameter of a method, block, or lambda definition.