docs: spell "filename" as a single word, like in most other occurrences

doc/nano.1

@@ -341,14 +341,14 @@ filename in the center of the title bar.
 .BR \-_ ", " \-\-minibar
 Suppress the title bar and instead show information about
 the current buffer at the bottom of the screen, in the space
-for the status bar.  In this "minibar" the file name is shown
+for the status bar.  In this "minibar" the filename is shown
 on the left, followed by an asterisk if the buffer has been modified.
 On the right are displayed the current line and column number, the
 code of the character under the cursor (in Unicode format: U+xxxx),
 the same flags as are shown by \fB\-\-stateflags\fR, and a percentage
 that expresses how far the cursor is into the file (linewise).
 When a file is loaded or saved, and also when switching between buffers,
-the number of lines in the buffer is displayed after the file name.
+the number of lines in the buffer is displayed after the filename.
 This number is cleared upon the next keystroke, or replaced with an
 [i/n] counter when multiple buffers are open.
 The line plus column numbers and the character code are displayed only when

doc/nano.texi

@@ -484,14 +484,14 @@ filename in the center of the title bar.
 @itemx --minibar
 Suppress the title bar and instead show information about
 the current buffer at the bottom of the screen, in the space
-for the status bar.  In this "minibar" the file name is shown
+for the status bar.  In this "minibar" the filename is shown
 on the left, followed by an asterisk if the buffer has been modified.
 On the right are displayed the current line and column number, the
 code of the character under the cursor (in Unicode format: U+xxxx),
 the same flags as are shown by @code{--stateflags}, and a percentage
 that expresses how far the cursor is into the file (linewise).
 When a file is loaded or saved, and also when switching between buffers,
-the number of lines in the buffer is displayed after the file name.
+the number of lines in the buffer is displayed after the filename.
 This number is cleared upon the next keystroke, or replaced with an
 [i/n] counter when multiple buffers are open.
 The line plus column numbers and the character code are displayed only when
@@ -937,14 +937,14 @@ The default value is "@t{(<[@{)>]@}}".
 @item set minibar
 Suppress the title bar and instead show information about
 the current buffer at the bottom of the screen, in the space
-for the status bar.  In this "minibar" the file name is shown
+for the status bar.  In this "minibar" the filename is shown
 on the left, followed by an asterisk if the buffer has been modified.
 On the right are displayed the current line and column number, the
 code of the character under the cursor (in Unicode format: U+xxxx),
 the same flags as are shown by @code{set stateflags}, and a percentage
 that expresses how far the cursor is into the file (linewise).
 When a file is loaded or saved, and also when switching between buffers,
-the number of lines in the buffer is displayed after the file name.
+the number of lines in the buffer is displayed after the filename.
 This number is cleared upon the next keystroke, or replaced with an
 [i/n] counter when multiple buffers are open.
 The line plus column numbers and the character code are displayed only when

doc/nanorc.5

@@ -185,14 +185,14 @@ The default value is "\fB(<[{)>]}\fP".
 .B set minibar
 Suppress the title bar and instead show information about
 the current buffer at the bottom of the screen, in the space
-for the status bar.  In this "minibar" the file name is shown
+for the status bar.  In this "minibar" the filename is shown
 on the left, followed by an asterisk if the buffer has been modified.
 On the right are displayed the current line and column number, the
 code of the character under the cursor (in Unicode format: U+xxxx),
 the same flags as are shown by \fBset stateflags\fR, and a percentage
 that expresses how far the cursor is into the file (linewise).
 When a file is loaded or saved, and also when switching between buffers,
-the number of lines in the buffer is displayed after the file name.
+the number of lines in the buffer is displayed after the filename.
 This number is cleared upon the next keystroke, or replaced with an
 [i/n] counter when multiple buffers are open.
 The line plus column numbers and the character code are displayed only when