Add c++ counterparts for java shuffleboard snippets (#2299)

* Add c++ counterparts for java shuffleboard snippets

* Add frc:: to c++ examples

Author: cfinn68916

source/docs/software/dashboards/shuffleboard/layouts-with-code/sending-data.rst

@@ -15,7 +15,7 @@ Sending simple data (numbers, strings, booleans, and arrays of these) is done by
 
    .. code-tab:: c++
 
-       Shuffleboard::GetTab("Numbers")
+       frc::Shuffleboard::GetTab("Numbers")
             .Add("Pi", 3.14);
 
 If data needs to be updated (for example, the output of some calculation done on the robot), call ``getEntry()`` after defining the value, then update it when needed or in a ``periodic`` function
@@ -52,6 +52,11 @@ Simply using `addPersistent` instead of `add` will make the value saved on the r
        Shuffleboard.getTab("Drive")
             .addPersistent("Max Speed", 1.0);
 
+   .. code-tab:: c++
+
+       frc::Shuffleboard::GetTab("Drive")
+            .AddPersistent("Max Speed", 1.0);
+
 Sending sensors, motors, etc
 ----------------------------
 
@@ -63,3 +68,8 @@ Analogous to ``SmartDashboard.putData``, any ``Sendable`` object (most sensors,
 
        Shuffleboard.getTab("Tab Title")
             .add("Sendable Title", mySendable);
+
+   .. code-tab:: c++
+
+       frc::Shuffleboard::GetTab("Tab Title")
+            .Add("Sendable Title", mySendable);