Add missing doc from PR github#1131 (github#1162)

Author: timvaillancourt

doc/command-line-flags.md

@@ -246,6 +246,14 @@ Provide a command delimited list of replicas; `gh-ost` will throttle when any of
 
 Provide an HTTP endpoint; `gh-ost` will issue `HEAD` requests on given URL and throttle whenever response status code is not `200`. The URL can be queried and updated dynamically via [interactive commands](interactive-commands.md). Empty URL disables the HTTP check.
 
+### throttle-http-interval-millis
+
+Defaults to 100. Configures the HTTP throttle check interval in milliseconds.
+
+### throttle-http-timeout-millis
+
+Defaults to 1000 (1 second). Configures the HTTP throttler check timeout in milliseconds.
+
 ### timestamp-old-table
 
 Makes the _old_ table include a timestamp value. The _old_ table is what the original table is renamed to at the end of a successful migration. For example, if the table is `gh_ost_test`, then the _old_ table would normally be `_gh_ost_test_del`. With `--timestamp-old-table` it would be, for example, `_gh_ost_test_20170221103147_del`.