Update docs

README.asciidoc

@@ -221,6 +221,7 @@ Contributors, sorted by the number of commits in descending order:
 * Samuel Loury
 * Peter Michely
 * Panashe M. Fundira
+* Lucas Hoffmann
 * Link
 * Larry Hynes
 * Johannes Altmanninger
@@ -234,7 +235,6 @@ Contributors, sorted by the number of commits in descending order:
 * Regina Hug
 * Mathias Fussenegger
 * Marcelo Santos
-* Lucas Hoffmann
 * Joel Bradshaw
 * Jean-Louis Fuchs
 * Franz Fellner

doc/help/settings.asciidoc

@@ -796,6 +796,8 @@ The proxy to use.
 
 In addition to the listed values, you can use a `socks://...` or `http://...` URL.
 
+This setting only works with Qt 5.8 or newer when using the QtWebEngine backend.
+
 Valid values:
 
  * +system+: Use the system wide proxy.
@@ -803,8 +805,6 @@ Valid values:
 
 Default: +pass:[system]+
 
-This setting is only available with the QtWebKit backend.
-
 [[network-proxy-dns-requests]]
 === proxy-dns-requests
 Whether to send DNS requests over the configured proxy.

qutebrowser/config/configdata.py

@@ -437,7 +437,9 @@ def data(readonly=False):
                                     else [usertypes.Backend.QtWebKit])),
              "The proxy to use.\n\n"
              "In addition to the listed values, you can use a `socks://...` "
-             "or `http://...` URL."),
+             "or `http://...` URL.\n\n"
+             "This setting only works with Qt 5.8 or newer when using the "
+             "QtWebEngine backend."),
 
             ('proxy-dns-requests',
              SettingValue(typ.Bool(), 'true',