Fix documentation warnings generated by JavaDoc (NFC) (#3428)

Some C++ Doxygen comments were updated to reflect any wording changes.

See `rg "(@return|@param \w+) TODO" | less` for list of incomplete docs.

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/button/Button.java

@@ -177,6 +177,7 @@ public class Button extends Trigger {
    *
    * @param command the command to start
    * @param interruptible whether the command is interruptible
+   * @return this button, so calls can be chained
    */
   public Button toggleWhenPressed(final Command command, boolean interruptible) {
     toggleWhenActive(command, interruptible);