r.out.gdal manual: added COG example (#1554)

* r.out.gdal manual: added COG example
* add links to GTiFF and COG man pages

raster/r.out.gdal/r.out.gdal.html

@@ -139,7 +139,7 @@ <h3>GeoTIFF caveats</h3>
 <p>Classic TIFF format supports only files with up to 4GB. Files that 
 exceed this limit (in compressed or uncompressed form) need to be 
 exported with <em>createopt="BIGTIFF=YES"</em>. BIGTIFF is available if 
-GDAL is built with libtiff >= 4.0.
+GDAL is built with libtiff &amp;= 4.0.
 
 <h3>Improving GeoTIFF compatibility</h3>
 
@@ -173,20 +173,32 @@ <h3>Improving GeoTIFF compatibility</h3>
 tags will be written and a World file is required (<em>createopt="TFW=YES"</em>).
 </ul>
 
+<!-- outdated?
 <p>
 Cloud Optimized GeoTIFFs (COG) can be created with the creation options 
 <em>createopt=TILED=YES,COMPRESS=DEFLATE</em>, followed by 
 <em>gdaladdo</em> to build overviews.
+-->
 
 <h2>EXAMPLES</h2>
 
 <h3>Export the integer raster basin_50K map to GeoTIFF format</h3>
 
+See also <a href="https://gdal.org/drivers/raster/gtiff.html">GeoTIFF format description</a> (GDAL):
+
 <div class="code"><pre>
 g.region raster=basin_50K -p
 r.out.gdal input=basin_50K output=basin_50K.tif
 </pre></div>
 
+<h3>Export the integer raster landclass96 map to Cloud Optimized GeoTIFF format</h3>
+
+See also <a href="https://gdal.org/drivers/raster/cog.html">Cloud Optimized GeoTIFF (COG) format description</a> (GDAL):
+
+<div class="code"><pre>
+g.region -p raster=landclass96
+r.out.gdal -fmt input=landclass96 output=landclass96.tif format=COG overviews=4
+</pre></div>
 
 <h3>Export a DCELL raster map in GeoTIFF format suitable for ESRI software</h3>
 
@@ -230,14 +242,6 @@ <h3>Export R,G,B imagery bands in GeoTIFF format suitable for ESRI software</h3>
 </pre></div>
 
 
-<h3>Export the floating point raster elevation map to ERDAS/IMG format</h3>
-
-<div class="code"><pre>
-g.region raster=elevation -p
-r.out.gdal input=elevation output=elelevation.img format=HFA type=Float32
-</pre></div>
-
-
 <h3>Export group of image maps as multi-band file</h3>
 <div class="code"><pre>
 g.list group
@@ -304,6 +308,17 @@ <h3>Export RGB with alpha channel that encodes NULL cells</h3>
 
 The resulting GeoTIFF file can be used e.g. for Web server applications.
 
+
+<h3>Export the floating point raster elevation map to ERDAS/IMG format</h3>
+
+See also <a href="https://gdal.org/drivers/raster/hfa.html">Erdas Imagine .img format description</a> (GDAL):
+
+<div class="code"><pre>
+g.region raster=elevation -p
+r.out.gdal input=elevation output=elelevation.img format=HFA type=Float32
+</pre></div>
+
+
 <h2>GDAL RELATED ERROR MESSAGES</h2>
 
 <ul>
@@ -324,9 +339,10 @@ <h2>GDAL RELATED ERROR MESSAGES</h2>
 
 <h2>SEE ALSO</h2>
 
-The <a href="http://www.gdal.org/formats_list.html">GDAL supported formats</a>
-page.
-<br>
+<a href="https://gdal.org/drivers/raster/index.html">GDAL supported raster formats</a> and
+<a href="https://gdal.org/drivers/vector/index.html">GDAL supported vector formats</a>
+
+<p>
 <em>
 <a href="r.out.ascii.html">r.out.ascii</a>,
 <a href="r.out.bin.html">r.out.bin</a>,
@@ -338,7 +354,7 @@ <h2>SEE ALSO</h2>
 
 <h2>REFERENCES</h2>
 
-GDAL Pages: <a href="http://www.gdal.org">http://www.gdal.org</a>
+GDAL Pages: <a href="http://gdal.org">https://gdal.org</a>
 
 
 <h2>AUTHORS</h2>