DOC: fix small typo in fe_id (backend instead of frontend)
Needs to be backported to 1.7 and 1.6 at least.
diff --git a/doc/configuration.txt b/doc/configuration.txt
index f24c396..f654c8e 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -13182,7 +13182,7 @@
fe_id : integer
Returns an integer containing the current frontend's id. It can be used in
- backends to check from which backend it was called, or to stick all users
+ backends to check from which frontend it was called, or to stick all users
coming via a same frontend to the same server.
fe_name : string