Doc'ing new "colorsrows" option

In manpage, and (via 'tuxpaint-docs' update) in OPTIONS docs.
Also, added a bash tab-completion entry for it.
(h/t Pere for enabling the feature.)

docs/es_ES.UTF-8/OPTIONS.txt

@@ -6,7 +6,7 @@ Options Documentation
           Copyright © 2002-2021 by various contributors; see AUTHORS.
                             http://www.tuxpaint.org/
 
-                                 22 enero 2021
+                                 5 febrero 2021
 
      ----------------------------------------------------------------------
 
@@ -714,6 +714,12 @@ Windows Users
              low halves of the byte, so "#FFF" is the same as "#FFFFFF", not
              "#F0F0F0".
 
+     colorsrows=ROWS
+
+             How many rows of color palette buttons to show; useful when
+             using a large color palette (see "colorfile", above), and/or for
+             use with coarse input devices (like eyegaze trackers).
+
      lang=LANGUAGE
 
              Run Tux Paint in one of the supported languages. Possible choice

docs/es_ES.UTF-8/html/OPTIONS.html

@@ -25,7 +25,7 @@
       </p>
 
       <p>
-        22 enero 2021      </p>
+         5 febrero 2021      </p>
     </center>
 
     <hr size="2"
@@ -953,6 +953,15 @@
             NOTES: You must separate decimal values with spaces, and begin hexadecimal values with a pound/number-sign character ("<code>#</code>"). In 3-digit hexadecimal, each digit is used for both the high and low halves of the byte, so "<code>#FFF</code>" is the same as "<code>#FFFFFF</code>", not "<code>#F0F0F0</code>".          </p>
         </dd>
 
+        <dt>
+          <code><b>colorsrows=<i>ROWS</i></b></code>
+        </dt>
+
+        <dd>
+          <p>
+            How many rows of color palette buttons to show; useful when using a large color palette (see "<code>colorfile</code>", above), and/or for use with coarse input devices (like eyegaze trackers).          </p>
+        </dd>
+
         <dt>
           <code><b>lang=<i>LANGUAGE</i></b></code>
         </dt>