Fixed typos in doxygen documentation (#481)

* Fixed typo in documentation.

* Fixed reference to removed function in remote config

Author: Alex Ames

performance/src/include/firebase/performance/trace.h

@@ -82,15 +82,15 @@ class Trace {
   /// @brief Gets the value of the metric identified by the metric_name or 0
   /// if it hasn't yet been set.
   ///
-  /// @param[in] matric_name The name of the metric to get the value of.
+  /// @param[in] metric_name The name of the metric to get the value of.
   /// @return The previously set of the given metric or 0 if it hasn't been
   /// set.
   int64_t GetLongMetric(const char* metric_name) const;
 
   /// @brief Increments the existing value of the given metric by
   /// increment_by or sets it to increment_by if the metric hasn't been set.
   ///
-  /// @param[in] matric_name The name of the metric to increment the value
+  /// @param[in] metric_name The name of the metric to increment the value
   /// of.
   /// @param[in] increment_by The value by which the metric should be
   /// incremented.

remote_config/src/include/firebase/remote_config.h

@@ -245,7 +245,8 @@ class RemoteConfig {
   ///
   /// @note This does not actually apply the data or make it accessible,
   /// it merely retrieves it and caches it.  To accept and access the newly
-  /// retrieved values, you must call @ref ActivateFetched().
+  /// retrieved values, you must call @ref Activate().
+  ///
   /// Note that this function is asynchronous, and will normally take an
   /// unspecified amount of time before completion.
   ///