fix: Add blank linkes before and after tables

Author: ap0llo

src/MarkdownGenerator.Test/Internal/_DocumentSerializer/DocumentSerializerTest.cs

@@ -315,6 +315,38 @@ public void Tables_are_serialized_as_expected_02() =>
                         new MdTableRow("Cell3", "Cell4")))
             );
 
+        [Fact]
+        public void Tables_are_preceded_by_a_blank_line() =>
+            AssertToStringEquals(
+                "___\r\n" +
+                "\r\n" +
+                "| Column1 | Column2 |\r\n" +
+                "| ------- | ------- |\r\n" +
+                "| Cell1   |         |\r\n" +
+                "| Cell3   | Cell4   |\r\n",
+                new MdDocument(
+                    new MdThematicBreak(),
+                    new MdTable(
+                        new MdTableRow("Column1", "Column2"),
+                        new MdTableRow("Cell1"),
+                        new MdTableRow("Cell3", "Cell4"))));
+
+        [Fact]
+        public void Tables_are_followed_by_a_blank_line() =>
+            AssertToStringEquals(
+                "| Column1 | Column2 |\r\n" +
+                "| ------- | ------- |\r\n" +
+                "| Cell1   |         |\r\n" +
+                "| Cell3   | Cell4   |\r\n" +
+                "\r\n" +
+                "___\r\n",
+                new MdDocument(
+                    new MdTable(
+                        new MdTableRow("Column1", "Column2"),
+                        new MdTableRow("Cell1"),
+                        new MdTableRow("Cell3", "Cell4")),
+                    new MdThematicBreak()));
+
         [Fact]
         public void Serializer_respects_the_TableStyle_serialization_option()
         {

src/MarkdownGenerator/Internal/_DocumentSerializer/DocumentSerializer.cs

@@ -312,6 +312,8 @@ void SaveRow(string[] row)
                 m_Writer.WriteLine(lineBuilder.ToString());
             }
 
+            m_Writer.RequestBlankLine();
+
             // save header row
             SaveRow(tableAsString[0]);
 
@@ -331,7 +333,9 @@ void SaveRow(string[] row)
             foreach(var row in tableAsString.Skip(1))
             {
                 SaveRow(row);
-            }            
+            }
+
+            m_Writer.RequestBlankLine();
         }
 
         public void SerializeHtmlTable(MdTable table)