DOC: just enlarge legend width

Author: Dengda98

docs/source/Module/ker2asc.rst

@@ -40,7 +40,7 @@ ker2asc
     gmt begin test png
         gmt plot stats -JX12c/3c -Bafg -BWSen -i0,1 -W0.5p,blue -l"Real"
         gmt plot stats -i0,2 -W0.5p,blue,-- -l"Imag"
-        gmt legend -DjTL+w1.5c+o0.1c -F+gwhite+c0.2p+p1p
+        gmt legend -DjTL+w2c+o0.1c -F+gwhite+c0.2p+p1p
     gmt end show