correction of typos after second spell ceck

examples/DateTime_Contructor_Test/DateTime_Contructor_Test.ino

@@ -89,7 +89,7 @@ void setup () {
     //auto tic{micros()};
     DateTime datetime = myRTC.now();
     //auto toc {micros()};
-    //Serial.print("\n\nDateTime Class instatiation duration: ");
+    //Serial.print("\n\nDateTime Class instantiation duration: ");
     //Serial.print(toc-tic);
     //Serial.println(" µs");
 

src/DS3231-RTC.cpp

@@ -150,7 +150,7 @@ void DateTime::set_timstamps() {
  * @param buffer buffer for time string 
  * @param buffersize size of buffer
  * @param formatSpec define format see strftime
- * @return size_t lenth of used buffer
+ * @return size_t length of used buffer
  */
 size_t DateTime::strf_DateTime(char *buffer, size_t buffersize, const char *formatSpec) {
    size_t len {strftime(buffer, buffersize, formatSpec, &_tm)};
@@ -180,7 +180,7 @@ DateTime RTClib::now(TwoWire & _Wire) {
     int16_t yday = calcYearDay(year, month, day);
     int16_t dst = -1;
 
-    // REMARK: add DST calculation if needed, but therfore timezone info is needed!
+    // REMARK: add DST calculation if needed, but therefore timezone info is needed!
     // use the complete set also yearday and dst for having a complete struct tm
     return DateTime{year, month, day, hour, min, sec, wday, yday, dst};
 }

src/DS3231-RTC.h

@@ -167,7 +167,7 @@ class DS3231 {
         *	1	0		0		0		Alarm when DoW, hour, min match
         *
         *	Note: byte AlarmBits is not explicitly cleared for the getAXTime methods to
-        *	support sequential retreival of both alarms with the same byte AlarmBits.
+        *	support sequential retrieval of both alarms with the same byte AlarmBits.
         *	Use the flag bool clearAlarmBits=True to explicitly clear byte AlarmBits on
         *  call to getAXTime.
         */