change default value of 'cookies-update' to 'true'

docs/configuration.rst

@@ -227,7 +227,7 @@ extractor.*.cookies-update
 --------------------------
 =========== =====
 Type        ``bool``
-Default     ``false``
+Default     ``true``
 Description If `extractor.*.cookies`_ specifies a cookies.txt file, update its
             contents with cookies received during data extraction.
 =========== =====

gallery_dl/extractor/common.py

@@ -202,7 +202,7 @@ class Extractor():
 
     def _store_cookies(self):
         """Store the session's cookiejar in a cookies.txt file"""
-        if self._cookiefile and self.config("cookies-update", False):
+        if self._cookiefile and self.config("cookies-update", True):
             cookiejar = http.cookiejar.MozillaCookieJar()
             for cookie in self._cookiejar:
                 cookiejar.set_cookie(cookie)