docs: improve guide

docs/userguides/config.md

@@ -184,7 +184,7 @@ ape plugins install .
 For Ape's HTTP usage, such as requests made via `web3.py`, optionally specify extra request headers.
 
 ```yaml
-request_header:
+request_headers:
   # NOTE: Only using Content-Type as an example; can be any header key/value.
   Content-Type: application/json
 ```
@@ -210,6 +210,8 @@ node:
     Content-Type: application/json
 ```
 
+To learn more about how request headers work in Ape, see [this section of the Networking guide](./networks.html#request-headers).
+
 ## Testing
 
 Configure your test accounts:

docs/userguides/networks.md

@@ -343,10 +343,17 @@ For the local network configuration, the default is `"max"`. Otherwise, it is `"
 ## Request Headers
 
 There are several layers of request-header configuration.
-Use the top-level request header config to configure headers for every request.
-Also, EVM-based and custom-ecosystems offer their own `request_headers:` config that gets used whenever using that ecosystem (regardless of network or provider).
-Then, each network, plugin or otherwise, has its own `request_headers:` config that gets used when using this network (regardless of provider).
-Finally, providers (such as the default `node` provider) typically offer a `request_headers:` config that gets used whenever using this provider (regardless of what network you are connecting to).
+They get merged into each-other in this order, with the exception being `User-Agent`, which has an append-behavior.
+
+- Default Ape headers (includes `User-Agent`)
+- Top-level configuration for headers (using `request_headers:` key)
+- Per-ecosystem configuration
+- Per-network configuration
+- Per-provider configuration
+
+Use the top-level `request_headers:` config to specify headers for every request.
+Use ecosystem-level specification for only requests made when connected to that ecosystem.
+Network and provider configurations work similarly; they are only used when connecting to that network or provider.
 
 Here is an example using each layer:
 
@@ -367,6 +374,9 @@ node:
     Provider-Level: "UseThisOnAllRequestsUsingNodeProvider"
 ```
 
+When using `User-Agent`, it will not override Ape's default `User-Agent` nor will each layer override each-other's.
+Instead, they are carefully appended to each other, allowing you to have a very customizable `User-Agent`.
+
 ## Local Network
 
 The default network in Ape is the local network (keyword `"local"`).