Pull request 203: AG-38975 Document pending requests

Merge in GO/adguard-home-wiki from AG-38975-upd-proxy to master

Squashed commit of the following:

commit 861a331583cd24e4f630a65a43820a259bccdc06
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Apr 14 19:00:59 2025 +0300

    Configuration: describe pending requests

Configuration.md

@@ -44,6 +44,7 @@ Options:
   --local-frontend                   Use local frontend directories.
   -v, --verbose                      Enable verbose output.
   --glinet                           Run in GL-Inet compatibility mode.
+  --no-permcheck                     Skip checking and migration of permissions of security-sensitive files.
   --version                          Show the version and exit.  Show more detailed version description with -v.
   --help                             Print this help.
 ```
@@ -564,6 +565,13 @@ Settings are stored in [YAML format](https://en.wikipedia.org/wiki/YAML), possib
       longer than 96 bits.  As per [RFC 6147][rfc6147], PTR requests are routed
       to the `local_ptr_upstreams` if the requested address is within either one
       of the configured prefixes or the default Well-Known one.
+
+    - `pending_requests` (**since v0.107.61**): The configuration for cache
+      poisoning attacks protection.
+        - `enabled`: Specifies, if AdGuard Home should track simultaneous
+          identical requests and perform a single lookup for them.  By default,
+          the value is `true`.
+
   - **ECS settings**
     - `edns_client_subnet` — Add EDNS Client Subnet (ECS) option to upstream
       requests and log the values sent by the clients in the query log.  Please
@@ -602,9 +610,9 @@ Settings are stored in [YAML format](https://en.wikipedia.org/wiki/YAML), possib
 
       The full list of proxy headers, in the order AdGuard Home inspects them:
       1.  `CF-Connecting-IP`
-      1.  `True-Client-IP`
-      1.  `X-Real-IP`
-      1.  `X-Forwarded-For`
+      2.  `True-Client-IP`
+      3.  `X-Real-IP`
+      4.  `X-Forwarded-For`
   - **DNS cache settings**
     - `cache_size` — DNS cache size (in bytes).
     - `cache_ttl_min` — The minimum TTL override, in seconds.  If the TTL of