Add hints: all deadlines refer to Hawaii Standard Time

Change-Id: I143c910cfb5c3426af5856b01c822f753ee1e094
diff --git a/templates/register.htm b/templates/register.htm
index 7d778ca..2f36e82 100644
--- a/templates/register.htm
+++ b/templates/register.htm
@@ -477,7 +477,7 @@
             <input type="checkbox" class="form-check-input" name="participation_confirmed" id="participate" required <?php echo isset($_POST[ 'participation_confirmed']) ? 'checked' : '' ?> oninput="update_total_due()" value="participation_confirmed">
             <label class="form-check-label fs-4" for="participation_confirmed">I confirm that I will attend the <?php echo $SERVICE_ACRONYM; ?> conference. 
                 <?php if(new DateTimeImmutable("now") <= new DateTimeImmutable($EARLYBIRD_DEADLINE." 23:59:59 HST")) {
-                        echo "The early bird conference fee <strong>€&nbsp;<span id='conference_fee'>". $EARLYBIRD_CONFERENCE_FEE."</span></strong> is valid until ".$EARLYBIRD_DEADLINE.".
+                        echo "The early bird conference fee <strong>€&nbsp;<span id='conference_fee'>". $EARLYBIRD_CONFERENCE_FEE."</span></strong> is valid until ".$EARLYBIRD_DEADLINE." (HST).
                      After that, the fee is €&nbsp;<span id='conference_fee'>". $REGULAR_CONFERENCE_FEE.".";
                         echo '<input type="hidden" name="conference_fee" value="' . $EARLYBIRD_CONFERENCE_FEE . '">';
                         echo '<input type="hidden" name="earlybird_registration" value="earlybird_registration">';
@@ -486,7 +486,7 @@
                         echo '<input type="hidden" name="conference_fee" value="' . $REGULAR_CONFERENCE_FEE . '">';
                         echo '<input type="hidden" name="earlybird_registration" value="">';
                     } ?>
-                    Registration will close after <?php echo $REGISTRATION_DEADLINE; ?>. The conference fee also covers the welcome reception and refreshments during coffee breaks.
+                    Registration will close after <?php echo $REGISTRATION_DEADLINE; ?> (HST). The conference fee also covers the welcome reception and refreshments during coffee breaks.
             </label>
             <div class="invalid-feedback">
                 You need to confirm your participation in order to proceed.
@@ -694,4 +694,4 @@
     <button name="type" value="register" type="submit" class="btn btn-primary float-right fs-3 fw-bold">Register for <?php echo $SERVICE_ACRONYM; ?></button>
 
 </form>
-</div>
\ No newline at end of file
+</div>