Typo fix.

docs/csaf_downloader.md

@@ -97,7 +97,7 @@ year they are from.
 
 You can ignore certain advisories while downloading by specifying a list
 of regular expressions to match their URLs by using the `ignorepattern` option. 
-E.g. `-i='.*white.*' -i='*.red.*'` will ignore files wich URLs contain the sub strings **white** or **red**.
+E.g. `-i='.*white.*' -i='*.red.*'` will ignore files which URLs contain the sub strings **white** or **red**.
 In the config file this has to be noted as:
 ```
 ignorepattern = [".*white.*", ".*red.*"]