Update synchronized attribute links to synchronized methods (#4323)

Note: Synchronized classes is a subheading of synchronized methods.

Author: ntrel

spec/attribute.dd

@@ -649,7 +649,7 @@ $(H3 $(LNAME2 gshared, $(D __gshared) Attribute))
 
 $(H3 $(LNAME2 synchronized, $(D synchronized) Attribute))
 
-        $(P See $(DDSUBLINK spec/class, synchronized-classes, Synchronized Classes).)
+        $(P See $(DDSUBLINK spec/class, synchronized-methods, Synchronized Methods).)
 
 
 $(H2 $(LNAME2 disable, $(D @disable) Attribute))

spec/declaration.dd

@@ -81,7 +81,7 @@ $(GNAME StorageClass):
     $(DDSUBLINK spec/class, abstract, `abstract`)
     $(DDSUBLINK spec/class, final, `final`)
     $(DDSUBLINK spec/function, virtual-functions, `override`)
-    $(DDSUBLINK spec/class, synchronized-classes, `synchronized`)
+    $(DDSUBLINK spec/class, synchronized-methods, `synchronized`)
     $(RELATIVE_LINK2 auto-declaration, `auto`)
     $(DDSUBLINK spec/attribute, scope, `scope`)
     $(DDLINK spec/const3, Type Qualifiers, `const`)

spec/statement.dd

@@ -2089,7 +2089,7 @@ void g(Object o)
         locked and unlocked as many times as there is recursion.
         )
 
-        $(P See also $(DDSUBLINK spec/class, synchronized-classes, synchronized classes).)
+        $(P See also $(DDSUBLINK spec/class, synchronized-methods, synchronized methods).)
 
 $(H2 $(LEGACY_LNAME2 TryStatement, try-statement, Try Statement))