Update documentation

Author: rzblue

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/DeferredCommand.java

@@ -11,9 +11,12 @@
 import java.util.function.Supplier;
 
 /**
- * Runs the given command when this command is initialized, and ends when it ends. Useful for
- * performing runtime tasks before creating a new command. If this command is interrupted, it will
- * cancel the command.
+ * Runs the command returned by the supplier when this command is initialized, and ends when it
+ * ends. Useful for performing runtime tasks before creating a new command. If this command is
+ * interrupted, it will cancel the command.
+ *
+ * <p>Note that the supplier <i>must</i> create a new Command each call. For selecting one of a
+ * preallocated set of commands, use {@link SelectCommand}.
  *
  * <p>This class is provided by the NewCommands VendorDep
  */

wpilibNewCommands/src/main/native/include/frc2/command/DeferredCommand.h

@@ -15,9 +15,12 @@
 
 namespace frc2 {
 /**
- * Runs the given command when this command is initialized, and ends when it
- * ends. Useful for performing runtime tasks before creating a new command. If
- * this command is interrupted, it will cancel the command.
+ * Runs the command returned by the supplier when this command is initialized,
+ * and ends when it ends. Useful for performing runtime tasks before creating a
+ * new command. If this command is interrupted, it will cancel the command.
+ *
+ * Note that the supplier <i>must</i> create a new Command each call. For
+ * selecting one of a preallocated set of commands, use SelectCommand.
  *
  * <p>This class is provided by the NewCommands VendorDep
  */