fix: do not replace comments with empty lines

Signed-off-by: Carlos A Becker <caarlos0@gmail.com>

testdata/readme.markdown.in

@@ -23,6 +23,8 @@ Check out the [Gold Style Gallery](https://github.com/charmbracelet/gold/blob/ma
 
 Currently `gold` uses the [Aurora ANSI colors](https://godoc.org/github.com/logrusorgru/aurora#Index).
 
+<!-- comments should be ignored -->
+
 ## Development
 
 Style definitions located in `styles/` can be embedded into the binary by
@@ -32,5 +34,14 @@ running [statik](https://github.com/rakyll/statik):
 statik -f -src styles -include "*.json"
 ```
 
+<!--
+multiline comments should also be ignored
+this is one comment with
+more than one
+line
+
+yup
+-->
+
 You can re-generate screenshots of all available styles by running `gallery.sh`.
 This requires `termshot` and `pngcrush` installed on your system!