std: fix a bunch of typos

The majority of these are in comments, some in doc comments which might
affect the generated documentation, and a few in parameter names -
nothing that should be breaking, however.

lib/std/Thread/Condition.zig

@@ -261,7 +261,7 @@ const FutexImpl = struct {
             const signals = (state & signal_mask) / one_signal;
 
             // Reserves which waiters to wake up by incrementing the signals count.
-            // Therefor, the signals count is always less than or equal to the waiters count.
+            // Therefore, the signals count is always less than or equal to the waiters count.
             // We don't need to Futex.wake if there's nothing to wake up or if other wake() threads have reserved to wake up the current waiters.
             const wakeable = waiters - signals;
             if (wakeable == 0) {

lib/std/Thread/Futex.zig

@@ -772,7 +772,7 @@ const PosixImpl = struct {
 
         waiter.event.wait(timeout) catch {
             // If we fail to cancel after a timeout, it means a wake() thread dequeued us and will wake us up.
-            // We must wait until the event is set as that's a signal that the wake() thread wont access the waiter memory anymore.
+            // We must wait until the event is set as that's a signal that the wake() thread won't access the waiter memory anymore.
             // If we return early without waiting, the waiter on the stack would be invalidated and the wake() thread risks a UAF.
             defer if (!cancelled) waiter.event.wait(null) catch unreachable;