Doc: Describe new Clangd preferences

- Updated screenshots
- Added option names and location to the change log

Task-number: QTCREATORBUG-30604
Change-Id: I1554d6b7dbd588619eb992ef906d1bcef056f8c5
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

dist/changelog/changes-14.0.0.md

@@ -56,9 +56,12 @@ Editing
       ([QTCREATORBUG-10279](https://bugreports.qt.io/browse/QTCREATORBUG-10279))
 * Clangd
     * Increased the minimum version to LLVM 17
-    * Added an option for the index location
+    * Added the `Per-project index location` and `Per-session index location`
+      options in `Preferences` > `C++` > `Clangd` for setting the index location
+      for a project or session
       ([QTCREATORBUG-27346](https://bugreports.qt.io/browse/QTCREATORBUG-27346))
-    * Made reparsing source files while editing header files optional
+    * Added the `Update dependent sources` option to make re-parsing source files
+      while editing header files optional
       ([QTCREATORBUG-29943](https://bugreports.qt.io/browse/QTCREATORBUG-29943))
     * Fixed the handling of system headers
       ([QTCREATORBUG-30474](https://bugreports.qt.io/browse/QTCREATORBUG-30474))

doc/qtcreator/src/editors/creator-only/creator-clang-codemodel.qdoc

@@ -243,9 +243,14 @@
             version 14, or later.
         \li In the \uicontrol {Background indexing} field, select \uicontrol Off
             to use a faster, but less accurate built-in indexer than the one used
-            by default. You can set the indexing priority depending on whether
+            by default. Set the indexing priority depending on whether
             the accuracy of results or speed is more important to you during
             global symbol searches.
+        \li In \uicontrol {Per-project index location}, select the folder to
+            store the index files for each project. The \c {compile-commands.json}
+            file is also stored in this folder.
+        \li In \uicontrol {Per-session index location}, select the folder to
+            store the index files for each session.
         \li In \uicontrol {Header/source switch mode}, select the C/C++
             backend for switching between header and source files. While the
             clangd implementation has more capabilities than the built-in
@@ -254,6 +259,13 @@
         \li By default, clangd attempts to use all unused cores. You can set a
             fixed number of cores to use in \uicontrol {Worker thread count}.
             Background indexing also uses this many worker threads.
+        \li Select \uicontrol {Insert header files on completion} to insert
+            header files when completing symbols.
+        \li Select \uicontrol {Update dependent sources} to re-parse all source
+            files that include a header file when editing the header file. This
+            can cause a heavy CPU load if the header file is included in many
+            source files. Clear this option to only re-parse the source files
+            when saving the header file.
         \li Set the number of \uicontrol {Completion results} if you regularly
             miss important results during code completion. Set it to 0 to remove
             the limit on the number of completion results. Setting this to 0 or a