resolve #98, remove unhelpful diagnostic

Author: tayloraswift

Sources/SymbolGraphLinker/StaticLinker.swift

@@ -578,19 +578,6 @@ extension StaticLinker
                 fallthrough
             }
 
-            diagnostic:
-            if  case nil = supplement.parsed.metadata.merge
-            {
-                guard
-                case nil = supplement.parsed.overview, supplement.parsed.details.isEmpty
-                else
-                {
-                    self.tables.diagnostics[supplement.source] =
-                        SupplementError.implicitConcatenation
-                    break diagnostic
-                }
-            }
-
             let body:MarkdownDocumentation = comment.parse(
                 using: self.doccommentParser,
                 with: &self.tables.diagnostics)

Sources/SymbolGraphLinker/Supplements/StaticLinker.SupplementError.swift

@@ -5,7 +5,6 @@ extension StaticLinker
 {
     enum SupplementError:Error, Equatable, Sendable
     {
-        case implicitConcatenation
         case multiple
         case untitled
     }
@@ -19,12 +18,6 @@ extension StaticLinker.SupplementError:Diagnostic
     {
         switch self
         {
-        case .implicitConcatenation:
-            output[.warning] = """
-            markdown supplement extends a symbol that already has a documentation comment, \
-            and no merge behavior was specified
-            """
-
         case .multiple:
             output[.warning] = """
             markdown supplement extends a symbol that already has a supplement