org-manual: Document Org Plot option "timeind"

* doc/org-manual.org (Plot options): Document "timeind".  Also fix the
formatting for a couple other entries.

doc/org-manual.org

@@ -2903,6 +2903,11 @@ For more information and examples see the [[https://orgmode.org/worg/org-tutoria
 
   Specify which column of the table to use as the =x= axis.
 
+- =timeind= ::
+
+  Specify which column of the table to use as the =x= axis as a time
+  value.
+
 - =deps= ::
 
   Specify the columns to graph as a Lisp style list, surrounded by
@@ -2910,7 +2915,7 @@ For more information and examples see the [[https://orgmode.org/worg/org-tutoria
   the third and fourth columns.  Defaults to graphing all other
   columns aside from the =ind= column.
 
-- transpose ::
+- =transpose= ::
 
   When =y=, =yes=, or =t= attempt to transpose the table data before
   plotting.  Also recognizes the shorthand option =trans=.
@@ -2945,21 +2950,21 @@ For more information and examples see the [[https://orgmode.org/worg/org-tutoria
   When plotting =3d= or =grid= types, set this to =t= to graph a flat
   mapping rather than a =3d= slope.
 
-- min ::
+- =min= ::
 
   Provides a minimum axis value that may be used by a plot type.
   Implicitly assumes the =y= axis is being referred to.  Can
   explicitly provide a value for a either the =x= or =y= axis with
  =xmin= and =ymin=.
 
-- max ::
+- =max= ::
 
   Provides a maximum axis value that may be used by a plot type.
   Implicitly assumes the =y= axis is being referred to.  Can
   explicitly provide a value for a either the =x= or =y= axis with
  =xmax= and =ymax=.
 
-- ticks ::
+- =ticks= ::
 
   Provides a desired number of axis ticks to display, that may be used
   by a plot type.  If none is given a plot type that requires ticks