Fix comment's typo (#12045)

Author: becomeStar

api/src/main/java/io/grpc/InternalConfigSelector.java

@@ -35,7 +35,7 @@ public abstract class InternalConfigSelector {
       = Attributes.Key.create("internal:io.grpc.config-selector");
 
   // Use PickSubchannelArgs for SelectConfigArgs for now. May change over time.
-  /** Selects the config for an PRC. */
+  /** Selects the config for an RPC. */
   public abstract Result selectConfig(LoadBalancer.PickSubchannelArgs args);
 
   public static final class Result {

core/src/main/java/io/grpc/internal/RetriableStream.java

@@ -382,7 +382,7 @@ public void runWith(Substream substream) {
     }
   }
 
-  /** Starts the first PRC attempt. */
+  /** Starts the first RPC attempt. */
   @Override
   public final void start(ClientStreamListener listener) {
     masterListener = listener;

xds/src/main/java/io/grpc/xds/package-info.java

@@ -15,7 +15,7 @@
  */
 
 /**
- * Library for gPRC proxyless service mesh using Envoy xDS protocol.
+ * Library for gRPC proxyless service mesh using Envoy xDS protocol.
  *
  * <p>The package currently includes a name resolver plugin and a family of load balancer plugins.
  * A gRPC channel for a target with {@code "xds:"} scheme will load the plugins and a