removed comment.char option from documentation (#6936)

* removed comment.char option from documentation

* Revert change to read.table() example call

---------

Co-authored-by: Ivan K <[email protected]>

Author: badasahog

src/fread.c

@@ -2762,7 +2762,7 @@ int freadMain(freadMainArgs _args) {
           DTWARN(_("Stopped early on line %"PRIu64". Expected %d fields but found %d. Consider fill=%d or even more based on your knowledge of the input file. Use fill=Inf for reading the whole file for detecting the number of fields. First discarded non-empty line: <<%s>>"),
           (uint64_t)DTi+row1line, ncol, tt, tt, strlim(skippedFooter,500));
         } else {
-          DTWARN(_("Stopped early on line %"PRIu64". Expected %d fields but found %d. Consider fill=TRUE and comment.char=. First discarded non-empty line: <<%s>>"),
+          DTWARN(_("Stopped early on line %"PRIu64". Expected %d fields but found %d. Consider fill=TRUE. First discarded non-empty line: <<%s>>"),
           (uint64_t)DTi+row1line, ncol, tt, strlim(skippedFooter,500));
         }
       }