In example code, add missing template parameter.

PiperOrigin-RevId: 622164857
Change-Id: I806ebeb4da81403c8a9d57f3529b2bfbc1a07d01

Author: Abseil Team

absl/profiling/internal/periodic_sampler.h

@@ -172,7 +172,7 @@ inline bool PeriodicSamplerBase::Sample() noexcept {
 // Typical use case:
 //
 //   struct HashTablezTag {};
-//   thread_local PeriodicSampler sampler;
+//   thread_local PeriodicSampler<HashTablezTag, 100> sampler;
 //
 //   void HashTableSamplingLogic(...) {
 //     if (sampler.Sample()) {