Incorrect session length number format in C# Examples

[taylorjp]

On line 90, when formatting the session length, the code uses the format "{0:N0}" which works fine for that example because the session length is 15 minutes (or 900 seconds). As soon as you get above a 999 second session length, however, that format adds commas to the result (ie 1,000), which breaks the embed. A better format would be "{0:D}" which would not add the commas.