[Export] remove extra spaces from Markdown, YAML exports

jrnl/plugins/markdown_exporter.py

@@ -57,7 +57,7 @@ class MarkdownExporter(TextExporter):
             date=date_str,
             title=entry.title,
             body=newbody,
-            space=""
+            space="\n"
         )
 
     @classmethod

jrnl/plugins/yaml_exporter.py

@@ -93,7 +93,7 @@ class YAMLExporter(TextExporter):
                 tags=', '.join([tag[1:] for tag in entry.tags]),
                 dayone=dayone_attributes,
                 body=newbody,
-                space=""
+                space="\n"
             )
 
     @classmethod