Added curl TIL to README

Author: jonasbn

README.md

@@ -287,6 +287,7 @@
 - [Handle gzip](curl/handle_gzip.md)
 - [How to handle location header](curl/how_to_handle_location_header.md)
 - [Ignore self signed certificates](curl/ignore_self_signed_certificates.md)
+- [usea config file](curl/use_a_config_file.md)
 
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