Fixed a couple of exercise references as they are no longer accurate after the recent changes

- Exercise 107 claimed the async exercises are 84-91, they are actually 85-94 and quiz 95
- Exercise 113 claimed the bit manip exercise is 097, it is now 100
- Exercise 114 has the bit manipulation exercises as 097 and 098, they are now 100 and 101
- Exercise 114 has the last switch exercise as being 108, it is now 111.

exercises/115_packed2.zig

@@ -1,5 +1,5 @@
 //
-// We've already learned about switch statements in exercises 030, 031 and 108.
+// We've already learned about switch statements in exercises 030, 031 and 111.
 // They also work with packed containers:
 
 const S = packed struct(u2) {