chore: doc interpreters

modules/server/src/main/scala/gql/server/interpreter/QueryInterpreter.scala

@@ -11,6 +11,9 @@ import gql._
 import gql.preparation._
 import cats.effect.std.Supervisor
 
+/** The [[QueryInterpreter]] will prepare a query for execution by inspecting the ast and planning the query accordingly.
+ *  Once all inputs have been prepared, the execution AST is passed to the [[SubqueryInterpreter]] for evaluation.
+  */
 trait QueryInterpreter[F[_]] {
   import QueryInterpreter._
 

modules/server/src/main/scala/gql/server/interpreter/StreamInterpreter.scala

@@ -11,6 +11,13 @@ import gql.preparation._
 import fs2.Stream
 import scala.concurrent.duration.FiniteDuration
 
+/** The [[StreamInterpreter]] is resposible for:
+ *   - Wireing together results for a query.
+ *   - Handling incoming asynchronous events.
+ *   - Handling resource lifetimes.
+ *
+ *  For actual query excution, take a look at [[QueryInterpreter]].
+  */
 trait StreamInterpreter[F[_]] {
   import StreamInterpreter._
 

modules/server/src/main/scala/gql/server/interpreter/SubqueryInterpreter.scala

@@ -29,6 +29,12 @@ import gql.resolver._
 import io.circe.syntax._
 import gql._
 
+/** The [[SubqueryInterpreter]] recursively runs through the AST and performs a multitude of tasks:
+ *    - Runs the [[Resolver]]/[[Step]]s defined in the query.
+ *    - Accumulates errors that occur during the evaluation of the query.
+ *    - Logs streams that have been subscribed to.
+ *    - Batches computations that have been marked as batchable.
+ */
 trait SubqueryInterpreter[F[_]] {
   type W[A] = WriterT[F, Chain[EvalFailure], A]