Add documentation

doc/geany.txt

@@ -509,6 +509,30 @@ order. It is not alphabetical as shown in the documents list
 See the `Notebook tab keybindings`_ section for useful
 shortcuts including for Most-Recently-Used document switching.
 
+Sorting tabs
+^^^^^^^^^^^^
+
+You can sort tabs based on the names of the opened files they represent,
+or based on the pathnames of those files.  This can be done by
+activating the sort command item in the popup menu that's shown by
+right-clicking an editor tab.  You can also activate the commands by
+using shortcut keys.  See `Notebook tab keybindings`_ section.
+
+Sorting based on filename means sorting based on the alphabetical order
+of the basic names of the files, which excludes the directory parts.
+For example: "name.ext".
+
+Sorting based on pathname on the other hand includes the directory
+parts.  This makes the resulting arrangement similar to the one in the
+documents list when Show Paths is enabled.
+
+Sorting tabs automatically
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Tabs can also be automatically sorted everytime a file or a group of
+files are opened.  This can be enabled in
+Preferences->Interface->Notebook tabs.  See `Editor tabs`_ section.
+
 Cloning documents
 ^^^^^^^^^^^^^^^^^
 The `Document->Clone` menu item copies the current document's text,
@@ -1967,6 +1991,15 @@ Double-clicking hides all additional widgets
     Whether to call the View->Toggle All Additional Widgets command
     when double-clicking on a notebook tab.
 
+Automatically sort tabs based on filename
+    Whether to automatically sort editor tabs based on their filenames
+    everytime files are opened.
+
+Automatically sort tabs based on pathname
+    Same as the one above but sort tabs based on pathname.  The result
+    would be the same as the one in documents list when directories are
+    shown.
+
 Tab positions
 `````````````
 
@@ -3707,6 +3740,13 @@ Move document right             Ctrl-Shift-PageDown       Changes the current do
 Move document first                                       Moves the current document to the first position.
 
 Move document last                                        Moves the current document to the last position.
+
+Sort tabs based on filename                               Sort tabs based on their filenames or base names.
+
+Sort tabs based on pathname                               Sort tabs based on their full path names.
+                                                          The tabs get sorted similar to how files are
+                                                          arranged in the documents list when Show Paths is
+                                                          enabled.
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