Doc: Update how-tos

- Fix menu paths to preferences
- Refer to existing screenshots of Preference pages
- Add information on setting preferences for
  automatically inserting matching characters
- Update the Completion preferences screenshot to show all options

Task-number: QTCREATORBUG-27560
Change-Id: Ib820c9bd19dc71ce109a4a59d40d6f276eb001ac
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

doc/qtcreator/src/howto/creator-only/creator-how-tos.qdoc

@@ -148,6 +148,8 @@
     To customize, import, or export keyboard shortcuts, select \uicontrol Edit >
     \uicontrol Preferences > \uicontrol Environment > \uicontrol Keyboard.
 
+    \image qtcreator-keyboard-shortcuts.png "Keyboard preferences"
+
     \section1 Run \QC from the command line
 
     You can launch \QC from the command line using the name of an
@@ -253,8 +255,12 @@
     create your own locator filters. That way you can locate files in a
     directory structure you have defined.
 
+    \image qtcreator-locator.png "List of locator filters"
+
     To create locator filters, select \uicontrol Edit > \uicontrol Preferences >
-    \uicontrol Locator > \uicontrol Add.
+    \uicontrol Environment > \uicontrol Locator > \uicontrol Add.
+
+    \image qtcreator-locator-customize.png "Locator preferences"
 
     For more information, see \l{Creating Locator Filters}.
 
@@ -273,9 +279,13 @@
 
     \section1 Add a license header template for C++ code
 
-    A file containing a license header for C++ can be specified under
-    \uicontrol Edit > \uicontrol Preferences > \uicontrol C++ >
-    \uicontrol {License Template}. It may contain special placeholders enclosed
+    Specify a file containing a license header for C++ in \uicontrol Edit >
+    \uicontrol Preferences > \uicontrol C++ > \uicontrol {File Naming} >
+    \uicontrol {License template}.
+
+    \image qtcreator-options-cpp-files.png "File Naming preferences"
+
+    The license file may contain special placeholders enclosed
     in \c{%%} that are replaced when generating a new file:
 
     \list 1
@@ -306,7 +316,7 @@
     \section1 Enclose selected code in curly braces, parentheses, or double quotes
 
     When you have selected code and enter one of the following opening
-    characters, the appropriate closing character is added automatically
+    characters, the matching closing character is added automatically
     at the end of the selection:
 
     \list
@@ -315,6 +325,12 @@
         \li "
     \endlist
 
+    To specify whether to automatically insert matching characters,
+    select \uicontrol Edit > \uicontrol Preferences >
+    \uicontrol {Text Editor} > \uicontrol Completion.
+
+    \image qtcreator-options-texteditor-completion.png "Completion preferences"
+
     \section1 Select the enclosing block in C++
 
     Press \key {Ctrl+U}.
@@ -325,6 +341,8 @@
     To open the editor, select \uicontrol Edit > \uicontrol Preferences
     > \uicontrol {Text Editor} > \uicontrol Snippets.
 
+    \image qtcreator-snippet-modifiers.png "Snippets preferences"
+
     For more information, see \l {Adding and Editing Snippets}.
 
     \section1 Quickly write down notes somewhere
@@ -344,10 +362,12 @@
 
     \section1 Configure the amount of recent files shown
 
-    Select \uicontrol Edit > \uicontrol Preferences, and change the value of the
-    list under \uicontrol Environment > \uicontrol System
+    Set the value of \uicontrol Edit > \uicontrol Preferences >
+    \uicontrol Environment > \uicontrol System
     > \uicontrol {Maximum number of entries in "Recent Files"}.
 
+    \image qtcreator-options-environment-system.png "System preferences"
+
     \section1 Search and replace across files using a regular expression
 
     As an example, say you want to replace equality checks (\c {foo == bar})