docs: clarify is experimental

Author: MilesCranmer

src/Expression.jl

@@ -27,7 +27,7 @@ end
 """
     AbstractExpression{T}
 
-Abstract type for user-facing expression types, which contain
+(Experimental) Abstract type for user-facing expression types, which contain
 both the raw expression tree operating on a value type of `T`,
 as well as associated metadata to evaluate and render the expression.
 
@@ -73,7 +73,7 @@ abstract type AbstractExpression{T} end
 """
     Expression{T, N, D} <: AbstractExpression{T}
 
-Defines a high level, user-facing, expression type that encapsulates an
+(Experimental) Defines a high-level, user-facing, expression type that encapsulates an
 expression tree (like `Node`) along with associated metadata for evaluation and rendering.
 
 # Fields

src/Parse.jl

@@ -2,13 +2,13 @@ module ParseModule
 
 using ..NodeModule: AbstractExpressionNode, Node, constructorof
 using ..OperatorEnumModule: AbstractOperatorEnum
-using ..OperatorEnumConstructionModule: empty_all_globals!
+using ..OperatorEnumConstructionModule: OperatorEnum, empty_all_globals!
 using ..ExpressionModule: AbstractExpression, Expression
 
 """
     @parse_expression(expr; operators, variable_names, node_type=Node, evaluate_on=[])
 
-Parse a symbolic expression `expr` into a computational graph where nodes represent operations or variables.
+(Experimental) Parse a symbolic expression `expr` into a computational graph where nodes represent operations or variables.
 
 ## Arguments