Time based media EO references (#4339)

fulfils request from @shawna-slh :
> While you are working on time-based media updates, would you be
willing to add to the Understanding documents — I guess in the the
Related Resources section if not elsewhere — links to the appropriate
pages of [Making Audio and Video Media
Accessible](https://urldefense.proofpoint.com/v2/url?u=https-3A__www.w3.org_WAI_media_av_&d=DwMDaQ&c=BSDicqBQBDjDI9RkVyTcHQ&r=vtHcRM9Rilx_mbg_xEVi75tHxIzcX-TB9HDH_GsS8Bk&m=smDbIzhHT9cuxTaPipqmcLILHJLZakg8ojLr0w1a8S1PPLRNql2Gx_X2HZhC5sR_&s=nXeeG_Dus63KkEn1ZhoxtjsOzVSSDw5De53_FBFJ4vY&e=)?
e.g., for [Understanding
1.2.2](https://urldefense.proofpoint.com/v2/url?u=https-3A__www.w3.org_WAI_WCAG22_Understanding_captions-2Dprerecorded&d=DwMDaQ&c=BSDicqBQBDjDI9RkVyTcHQ&r=vtHcRM9Rilx_mbg_xEVi75tHxIzcX-TB9HDH_GsS8Bk&m=smDbIzhHT9cuxTaPipqmcLILHJLZakg8ojLr0w1a8S1PPLRNql2Gx_X2HZhC5sR_&s=r75GZdQtZtwZ7iQyHnr_5KLOO-Xg4Y6ILZDz2s4y9AY&e=)
add link to
[Captions/Subtitles](https://urldefense.proofpoint.com/v2/url?u=https-3A__www.w3.org_WAI_media_av_captions_&d=DwMDaQ&c=BSDicqBQBDjDI9RkVyTcHQ&r=vtHcRM9Rilx_mbg_xEVi75tHxIzcX-TB9HDH_GsS8Bk&m=smDbIzhHT9cuxTaPipqmcLILHJLZakg8ojLr0w1a8S1PPLRNql2Gx_X2HZhC5sR_&s=Ax1GhCwDvzqNKG5_rs2qijx94yR4wNzSOj3tMz7rvPE&e=)
in Making Audio and Video Media Accessible.

I added an items to the Resources section of the A and AA Understanding
docs, and in AAA where there was material that seemed to be specific to
the SC. Six in total.

Also
resolves #4341
I added in some trivial corrections to the 1.2 Time-based media
understanding doc to close a recent issue.

---------

Co-authored-by: Patrick H. Lauke <redux@splintered.co.uk>
Co-authored-by: Hidde de Vries <160571138+hidde-logius@users.noreply.github.com>

Author: 3 people

understanding/20/audio-description-or-media-alternative-prerecorded.html

@@ -147,6 +147,10 @@ <h2>Resources for Audio Description or Media Alternative (Prerecorded)</h2>
 
 
       <ul>
+         <li>
+
+            <a href="https://www.w3.org/WAI/media/av/">Making Audio and Video Media Accessible, W3C Web Accessibility Initiative (WAI)</a>
+         </li>
 
          <li>
 

understanding/20/audio-description-prerecorded.html

@@ -116,6 +116,11 @@ <h2>Resources for Audio Description (Prerecorded)</h2>
 
       <ul>
 
+         <li>
+
+            <a href="https://www.w3.org/WAI/media/av/description/">Description of Visual Information</a>, in <a href="https://www.w3.org/WAI/media/av/">Making Audio and Video Media Accessible</a>, W3C Web Accessibility Initiative (WAI)
+         </li>
+         
          <li>
 
             <a href="http://ncam.wgbh.org/invent_build/web_multimedia/accessible-digital-media-guide/guideline-h-multimedia#techH12">NCAM Rich Media Accessibility, Accessible SMIL Templates</a>

understanding/20/audio-only-and-video-only-prerecorded.html

@@ -116,6 +116,12 @@ <h2>Resources for Audio-only and Video-only (Prerecorded)</h2>
 
 
       <ul>
+
+         <li>
+
+            <a href="https://www.w3.org/WAI/media/av/">Making Audio and Video Media Accessible, W3C Web Accessibility Initiative (WAI)</a>
+         </li>
+         
 
          <li>
 

understanding/20/captions-prerecorded.html

@@ -111,6 +111,10 @@ <h2>Resources for Captions (Prerecorded)</h2>
          <h3>Guides to Captioning</h3>
 
          <ul>
+
+            <li>
+                           <a href="https://www.w3.org/WAI/media/av/captions/">Captions/Subtitles</a>, in <a href="https://www.w3.org/WAI/media/av/">Making Audio and Video Media Accessible</a>, W3C Web Accessibility Initiative (WAI)
+            </li>
 
             <li>
                <a href="https://www.bbc.co.uk/accessibility/forproducts/guides/subtitles/">BBC: Subtitle Guidelines</a>

understanding/20/media-alternative-prerecorded.html

@@ -108,7 +108,13 @@ <h2>Resources for Media Alternative (Prerecorded)</h2>
 
 
       <ul>
-         
+
+         <li>
+
+            <a href="https://www.w3.org/WAI/media/av/transcripts/">Transcripts</a>, in <a href="https://www.w3.org/WAI/media/av/">Making Audio and Video Media Accessible</a>, W3C Web Accessibility Initiative (WAI)
+
+         </li>
+
          <li>
 
             <a href="http://www.uiaccess.com/transcripts/transcript_services.html">uiAccess list of transcription services</a>

understanding/20/sign-language-prerecorded.html

@@ -85,6 +85,12 @@ <h2>Resources for Sign Language (Prerecorded)</h2>
 
       <ul>
 
+         <li>
+
+            <a href="https://www.w3.org/WAI/media/av/sign-languages/">Sign Languages</a>, in <a href="https://www.w3.org/WAI/media/av/">Making Audio and Video Media Accessible</a>, W3C Web Accessibility Initiative (WAI)
+
+         </li>
+         
          <li>
 
             <a href="https://www.w3.org/TR/REC-smil/">Synchronized Multimedia Integration Language (SMIL) 1.0</a>

understanding/20/time-based-media.html

@@ -14,7 +14,7 @@ <h2>Intent of Time-Based Media</h2>
 
 
       <p>The purpose of this guideline is to provide access to time-based and synchronized
-         media.This includes media that is:
+         media. This includes media that is:
       </p>
 
       <ul>
@@ -36,9 +36,7 @@ <h2>Intent of Time-Based Media</h2>
 
       <p>For 
          <strong>audio-only</strong> or 
-         <strong>video-only</strong> media, you only need to apply the success criteria that say "
-         <strong>audio-only</strong>" or "
-         <strong>video-only</strong>" in their short name. If your media is not 
+         <strong>video-only</strong> media, you only need to apply the success criteria that say "<strong>audio-only</strong>" or "<strong>video-only</strong>" in their short name. If your media is not 
          <strong>audio-only</strong> or 
          <strong>video-only</strong>, then all the rest of the success criteria apply.
       </p>