DOC: configuration: add the httpclient keywords to the global keywords index

    - httpclient.ssl.verify
    - httpclient.ssl.ca-file
    - httpclient.resolvers.id
    - httpclient.resolvers.prefer
diff --git a/doc/configuration.txt b/doc/configuration.txt
index cab37b3..23fc72b 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -1008,6 +1008,10 @@
    - grace
    - group
    - hard-stop-after
+   - httpclient.resolvers.id
+   - httpclient.resolvers.prefer
+   - httpclient.ssl.ca-file
+   - httpclient.ssl.verify
    - h1-case-adjust
    - h1-case-adjust-file
    - insecure-fork-wanted