[wpimath] Use newer link to controls book in comments (NFC) (#2700)

wpimath/src/main/native/include/frc/geometry/Pose2d.h

@@ -151,8 +151,8 @@ class Pose2d {
   /**
    * Obtain a new Pose2d from a (constant curvature) velocity.
    *
-   * See <https://file.tavsys.net/control/state-space-guide.pdf> section on
-   * nonlinear pose estimation for derivation.
+   * See https://file.tavsys.net/control/controls-engineering-in-frc.pdf section
+   * 10.2 "Pose exponential" for a derivation.
    *
    * The twist is a change in pose in the robot's coordinate frame since the
    * previous pose update. When the user runs exp() on the previous known

wpimath/src/main/native/include/frc/system/LinearSystem.h

@@ -23,7 +23,7 @@ namespace frc {
  * A plant is a mathematical model of a system's dynamics.
  *
  * For more on the underlying math, read
- * https://file.tavsys.net/control/state-space-guide.pdf.
+ * https://file.tavsys.net/control/controls-engineering-in-frc.pdf.
  */
 template <int States, int Inputs, int Outputs>
 class LinearSystem {

wpimath/src/main/native/include/frc/system/LinearSystemLoop.h

@@ -29,7 +29,7 @@ namespace frc {
  * input because that's what comes back from the sensors).
  *
  * For more on the underlying math, read
- * https://file.tavsys.net/control/state-space-guide.pdf.
+ * https://file.tavsys.net/control/controls-engineering-in-frc.pdf.
  */
 template <int States, int Inputs, int Outputs>
 class LinearSystemLoop {