docs: replace screenshot and add sources

Signed-off-by: Conrad Zelck <git@simpel.cc>

README.md

 # Comment Syntax Finder
-Web page listing inline and block comments for about 150 programming and scripting languages.
+Web page listing inline and block comments for about 777 programming and scripting languages.
 Filter this list with the search input.
 
 ![screenshot](screenshot.png)
 
 ## Remarks
 - search input filters both language and syntax
-- `~` is the replacement for the comment text itself
+- column "type" shows whether the comment is line (L) or multiline (M) comment
+
+## Sources
+- [en.wikipedia.org/wiki/Comparison_of_programming_languages_(syntax)](https:en.wikipedia.org/wiki/Comparison_of_programming_languages_(syntax))
+- [rigaux.org/language-study/syntax-across-languages/Vrs.html](https:rigaux.org/language-study/syntax-across-languages/Vrs.html)
+- [pldb.com/languages/line-comments-feature.html](https:pldb.com/languages/line-comments-feature.html)
+- [pldb.com/languages/multiline-comments-feature.html](https:pldb.com/languages/multiline-comments-feature.html)