Doc: Describe Extensions mode

Task-number: QTCREATORBUG-30604
Change-Id: I5a3b9eadfccfbf759097d48e8cc506d697f53864
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

doc/qtcreator/src/howto/creator-help.qdoc

@@ -42,7 +42,7 @@
     The following image shows the context sensitive help in the \uicontrol Edit
     mode.
 
-    \image qtcreator-context-sensitive-help.png {Context-sensitive help in Edit mode}
+    \image qtcreator-context-sensitive-help.webp {Context-sensitive help in Edit mode}
 
     \section1 Change the font
 
@@ -287,7 +287,7 @@
     code editor when you press \key F1. If there is not enough vertical
     space, the help opens in the full-screen help mode.
 
-    \image qtcreator-context-sensitive-help.png {Context-sensitive help in Edit mode}
+    \image qtcreator-context-sensitive-help.webp {Context-sensitive help in Edit mode}
 
     To specify that the help always opens in full-screen mode or in an external
     window, go to \preferences > \uicontrol Help > \uicontrol General.

doc/qtcreator/src/howto/creator-only/creator-how-to-install-extensions.qdoc

@@ -0,0 +1,39 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
+
+/*!
+    \page creator-how-to-load-extensions.html
+    \previouspage creator-how-tos.html
+
+    \ingroup creator-how-to-use
+
+    \title Load extensions
+
+    In the experimental \uicontrol Extensions mode, you can load and unload
+    extensions from the computer or the web.
+
+    To load extensions when you start \QC:
+
+    \list 1
+        \li Go to \uicontrol Extensions.
+            \image qtcreator-extension-mode.webp {Extensions mode}
+        \li Select an extension.
+        \li Select \uicontrol {Load on start}.
+    \endlist
+
+    \section1 Load extensions from the web
+
+    By default, the \uicontrol Extensions mode lists extensions installed on the
+    computer. You can also list extensions from external repositories in the web.
+
+    To load extensions from the web:
+
+    \list 1
+        \li Go to \preferences > \uicontrol Environment > \uicontrol Extensions.
+            \image qtcreator-preferences-extensions.webp {Extensions in Preferences}
+        \li Select \uicontrol {Use external repository}.
+        \li Select \uicontrol OK.
+    \endlist
+
+    \sa {Enable and disable plugins}, {Install plugins}
+*/

doc/qtcreator/src/overview/creator-only/creator-keyboard-shortcuts.qdoc

@@ -141,8 +141,11 @@
             \li  Switch to \uicontrol Projects mode
             \li  Ctrl+5
         \row
-            \li  Switch to \uicontrol Help mode
+            \li  Switch to \uicontrol Extensions mode
             \li  Ctrl+6
+        \row
+            \li  Switch to \uicontrol Help mode
+            \li  Ctrl+7
         \row
             \li  Toggle \uicontrol{Issues}
             \li  Alt+1 (Cmd+1 on \macos)

doc/qtcreator/src/user-interface/creator-only/creator-how-to-switch-between-modes.qdoc

@@ -27,7 +27,7 @@
         \li Purpose
         \li Read More
     \row
-        \li {1,7} \inlineimage qtcreator-mode-selector.png
+        \li {1,8} \inlineimage qtcreator-mode-selector.webp {Mode selector}
     \row
         \li \uicontrol Welcome
         \li \key Ctrl+1
@@ -57,8 +57,13 @@
             This mode is available when a project is open.
         \li \l{Configuring Projects}
     \row
-        \li \uicontrol Help
+        \li \uicontrol Extensions
         \li \key Ctrl+6
+        \li Load \QC extensions from the computer or the web.
+        \li \l{Load extensions}
+    \row
+        \li \uicontrol Help
+        \li \key Ctrl+7
         \li Read documentation.
         \li \l{Get help}
     \endtable

doc/qtcreator/src/user-interface/creator-ui.qdoc

@@ -16,7 +16,7 @@
     \if defined(qtcreator)
     When you start \QC, it opens to the \uicontrol Welcome mode.
 
-    \image qtcreator-breakdown.png {Welcome mode}
+    \image qtcreator-welcome.webp {Welcome mode}
 
     \table
     \header