Update pw-change.html, register.html, submit.html

Some images are no longer used but they still exist here for the time
being. Text is used instead though based on some discussion text might
have to change.

Adjusted alt text of some images a bit.

A more thorough look at the way these updates look must still be done.

next/register.html

@@ -442,11 +442,11 @@ in order to register for the IOCCC.</p>
 </ul>
 <p><strong>NOTE</strong>: For submissions with multiple authors, only one author needs to subscribe.</p>
 <p><img src="../png/register.0_531x445-signup.png"
- alt="signup for a mailing list"
+ alt="signup for a mailing list screenshot"
  width=531 height=445></p>
 <p>After clicking <strong>((Next &gt;&gt;))</strong>, you will be notified that you will receive an email:</p>
 <p><img src="../png/register.1_633x163-verify.png"
- alt="verify your email notification"
+ alt="verify your email notification screenshot"
  width=633 height=163></p>
 <div id="step_c">
 <h2 id="step-c-open-the-subscription-consent-email-message">Step C: Open the Subscription consent email message</h2>
@@ -470,7 +470,7 @@ you have tried a few times, <a href="../contact.html">Contact the IOCCC</a> to a
 <code>https://www.freelists.org/v/ioccc28-reg/SOME-RANDOM-STUFF</code>.</p>
 <p>Click on that link. The email might look the below:</p>
 <p><img src="../png/register.2_590x253-verify-email.png"
- alt="Subscription consent email"
+ alt="Subscription consent email screenshot"
  width=590 height=253></p>
 <p><strong>NOTE</strong>: If you prefer to <strong>NOT</strong> click links in email, simply copy that
 URL from your “Subscription consent email” and paste it into your browser.</p>
@@ -479,7 +479,7 @@ URL from your “Subscription consent email” and paste it into your browser.</
 </div>
 <p>In your browser, for the link referenced in <a href="#step_c">Step C</a>, click the <strong>((Next &gt;&gt;))</strong> button.</p>
 <p><img src="../png/register.3_428x205-confirm.png"
- alt="confirm your email"
+ alt="confirm your email screenshot"
  width=428 height=205></p>
 <div id="step_e">
 <h2 id="step-e-verify-you-have-read-the-mailing-list-polices-and-that-you-consent-to-receiving-emails">Step E: Verify you have read the mailing list polices and that you consent to receiving emails</h2>
@@ -493,11 +493,11 @@ URL from your “Subscription consent email” and paste it into your browser.</
 <p>Once you have done this by clicking the 3 checkboxes, click the <strong>((Next &gt;&gt;))</strong>
 button:</p>
 <p><img src="../png/register.4_657x446-subscribe.png"
- alt="complete subscription"
+ alt="complete subscription screenshot"
  width=657 height=446></p>
 <p>After clicking <strong>((Next &gt;&gt;))</strong>, you will be notified that you will receive an email:</p>
 <p><img src="../png/register.5_487x154-done.png"
- alt="registration is complete"
+ alt="registration is complete screenshot"
  width=487 height=154></p>
 <div id="step_f">
 <h2 id="step-f-read-the-welcome-email">Step F: Read the Welcome email</h2>
@@ -507,7 +507,7 @@ button:</p>
 <pre><code>    Welcome to &#39;ioccc28-reg&#39;</code></pre>
 <p>Read the “Welcome” email.</p>
 <p><img src="../png/register.6_413x657-welcome.png"
- alt="Welcome email"
+ alt="Welcome email screenshot"
  width=414 height=657></p>
 <p><strong>NOTE</strong>: The “Welcome” email is usually sent by the FreeLists
 List Manager within a minute after clicking the <strong>((Next &gt;&gt;))</strong> button.