[pexels] add support (#2286, #4214, #6769)

docs/configuration.rst

@@ -404,6 +404,7 @@ Default
         ``zerochan``
     * ``"1.0-2.0"``
         ``flickr``,
+        ``pexels``,
         ``weibo``,
         ``[wikimedia]``
     * ``"1.4"``

docs/gallery-dl.conf

@@ -128,7 +128,7 @@
         },
         "bilibili":
         {
-            "sleep-request": "2.0-4.0"
+            "sleep-request": "3.0-6.0"
         },
         "bluesky":
         {
@@ -438,6 +438,10 @@
             "files"        : ["images", "image_large", "attachments", "postfile", "content"],
             "format-images": "download_url"
         },
+        "pexels":
+        {
+            "sleep-request": "1.0-2.0"
+        },
         "pillowfort":
         {
             "username": "",

docs/supportedsites.md

@@ -667,6 +667,12 @@ Consider all listed sites to potentially be NSFW.
     <td>Creators, Posts, User Profiles</td>
     <td><a href="https://github.com/mikf/gallery-dl#cookies">Cookies</a></td>
 </tr>
+<tr>
+    <td>Pexels</td>
+    <td>https://pexels.com/</td>
+    <td>Collections, individual Images, Search Results, User Profiles</td>
+    <td></td>
+</tr>
 <tr>
     <td>PhotoVogue</td>
     <td>https://www.vogue.com/photovogue/</td>