Add migration guide for going to v2.x.x.

Author: czjaso

MigrationGuide.md

@@ -6,8 +6,7 @@ With coreSNTP versions >=v2.0.0, there are breaking changes that need to be addr
 
 * The `Sntp_ConvertToUnixTime` function now uses `uint32_t *` instead of `UnixTime_t *` for the Unix time seconds parameter. This change was made because:
   - A `uint32_t` Unix timestamp can represent dates until February 7, 2106 06:28:15 UTC
-  - Beyond this date, we cannot differentiate between NTP era 0 and era 1 timestamps
-  - This provides a more accurate representation of the library's actual capabilities
+  - Beyond this date, we cannot differentiate between NTP era 0 and era 1 timestamps, thus it does not need to be a `uint64_t`
 
 Thus, the signature of `Sntp_ConvertToUnixTime` changed from:
 ```c
@@ -36,12 +35,6 @@ SntpStatus_t status;
 // Assume sntpTime has been populated from an SNTP response
 
 status = Sntp_ConvertToUnixTime( &sntpTime, &unixTimeSecs, &unixTimeMicrosecs );
-
-if( status == SntpSuccess )
-{
-    // Use the Unix time
-    printf( "Unix time: %llu.%06u\n", ( unsigned long long ) unixTimeSecs, unixTimeMicrosecs );
-}
 ```
 
 **New Code Snippet**:
@@ -54,16 +47,4 @@ SntpStatus_t status;
 // Assume sntpTime has been populated from an SNTP response
 
 status = Sntp_ConvertToUnixTime( &sntpTime, &unixTimeSecs, &unixTimeMicrosecs );
-
-if( status == SntpSuccess )
-{
-    // Use the Unix time
-    printf( "Unix time: %u.%06u\n", unixTimeSecs, unixTimeMicrosecs );
-}
-```
-
-### Additional Changes
-
-* **Year 2038 Problem Fixed**: The library now properly handles timestamps beyond January 19, 2038 03:14:07 UTC (the traditional Unix timestamp overflow point for 32-bit signed integers). The library uses unsigned 32-bit integers and can represent dates until February 7, 2106.
-
-* **Improved Time Conversion**: The `Sntp_ConvertToUnixTime` function now includes proper overflow and underflow checking to ensure time conversions are handled safely.
+```