Modify HTML to work better with manpages

  (avoid using block-level elements inside <td> unnecessarily)


git-svn-id: https://svn.osgeo.org/grass/grass/trunk@32988 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.slope.aspect/r.slope.aspect.html

@@ -35,12 +35,12 @@ radius of curvature of 20m.
 <table width="100%" border="0">
  <tr valign="baseline">
   <td>
-  <div align="center">
+  <center>
     <img src="dem.png" border="1">
     <P>
     Example DEM
     <BR><BR>
-  </div>
+  </center>
   </td>
   <td>
   </td>
@@ -48,39 +48,39 @@ radius of curvature of 20m.
 
  <tr valign="baseline">
   <td>
-  <div align="center">
+  <center>
     <img src="slope.png" border="1">
     <P>
     Slope (degree) from example DEM
     <BR><BR>
-  </div>
+  </center>
   </td>
   <td>
-  <div align="center">
+  <center>
     <img src="aspect.png" border="1">
     <P>
     Aspect (degree) from example DEM
     <BR><BR>
-  </div>
+  </center>
   </td>
  </tr>
 
  <tr valign="baseline">
   <td>
-  <div align="center">
+  <center>
     <img src="tcurv.png" border="1">
     <P>
     Tangential curvature (m<sup>-1</sup>) from example DEM
     <BR><BR>
-  </div>
+  </center>
   </td>
   <td>
-  <div align="center">
+  <center>
     <img src="pcurv.png" border="1">
     <P>
     Profile curvature (m<sup>-1</sup>) from example DEM
     <BR><BR>
-  </div>
+  </center>
   </td>
   <td>
   </td>