Fix #12776: Mistake in API documentation

Elapsed months after one year was mistakenly said to be 16.
Now it states the correct value at the beginning of the game and the increase every month and year.

distribution/openrct2.d.ts

@@ -371,7 +371,8 @@ declare global {
          */
         readonly ticksElapsed: number;
         /**
-         * The total number of months that have elapsed. This will equate to 16 on 1st March, Year 2.
+         * The total number of months that have elapsed. This will equate to 0 in March, Year 1 and
+         * increase by 1 every month, i.e. by 8 every year.
          * Note: this represents the current date and may be reset by cheats or scripts.
          */
         monthsElapsed: number;