Fix paragraph break issue in nimc.txt. Add spacing to command line options table.

config/nimdoc.cfg

@@ -609,6 +609,10 @@ table {
   border-collapse: collapse;
   border-spacing: 0; }
 
+table th, table td {
+  padding: 0px 8px 0px;
+}
+
 .table {
   width: 100%;
   margin-bottom: 20px; }

doc/basicopt.txt

@@ -1,4 +1,5 @@
-Usage::
+::
+
     nim command [options] [projectfile] [arguments]
 
 Command:

doc/nimc.txt

@@ -30,8 +30,12 @@ Command line switches
 ---------------------
 Basic command line switches are: 
 
+Usage:
+
 .. include:: basicopt.txt
 
+----
+
 Advanced command line switches are:
 
 .. include:: advopt.txt