feat(doc): update for PAC file use and new priority

Author: jmkerloch

docs/guides/howto_behind_proxy.md

@@ -1,7 +1,7 @@
 # How to use behind a network proxy
 
 :::{info}
-Only HTTP and HTTPS proxies are supported. No socks, no PAC.
+Only HTTP and HTTPS proxies are supported. No socks. Automatic values definition from PAC file available.
 :::
 
 > See [Requests official documentation](https://docs.python-requests.org/en/latest/user/advanced/#proxies)
@@ -19,9 +19,13 @@ qdt --proxy-http "http://user:[email protected]:8765"
 
 ## Using environment variables
 
-### Generic `HTTP_PROXY` and `HTTPS_PROXY`
+For proxy definition, QDT use this order of priority:
 
-- it allows a specific URL by protocol (scheme)
+- `QDT_PROXY_HTTP`
+- `QDT_PAC_FILE`
+- PAC file from system
+- Proxy configuration from system
+- Generic `HTTP_PROXY` and `HTTPS_PROXY`
 
 ### Custom `QDT_PROXY_HTTP`
 
@@ -32,10 +36,12 @@ qdt --proxy-http "http://user:[email protected]:8765"
 
 [PAC file](https://developer.mozilla.org/en-US/docs/Web/HTTP/Proxy_servers_and_tunneling/Proxy_Auto-Configuration_PAC_file) can be used by SysAdmin to define proxy with a set of rules depending on the url.
 
-For QDT, PAC file can be used if no environment variable for proxy are already defined (`HTTP_PROXY`,`HTTPS_PROXY`, `QDT_PROXY_HTTP`).
-
 [PyPac](https://pypac.readthedocs.io/en/latest/) is used for PAC file management. By default we are using the PAC file defined by system but a custom PAC file can be defined with `QDT_PAC_FILE` environment variable (local file or url).
 
+### Generic `HTTP_PROXY` and `HTTPS_PROXY`
+
+- it allows a specific URL by protocol (scheme)
+
 #### Example on Windows PowerShell
 
 Only for the QDT command scope:

docs/usage/settings.md

@@ -28,6 +28,7 @@ Some others parameters can be set using environment variables.
 | `QDT_STREAMED_DOWNLOADS` | If set to `false`, the content of remote files is fully downloaded before being written locally. | `true` |
 | `QDT_SSL_USE_SYSTEM_STORES` | By default, a bundle of SSL certificates is used, through [certifi](https://pypi.org/project/certifi/). If this environment variable is set to `true`, QDT tries to uses the system certificates store. Based on [truststore](https://truststore.readthedocs.io/). See also [How to use custom SSL certificates](../guides/howto_use_custom_ssl_certs.md).  | `False` |
 | `QDT_SSL_VERIFY` | Enables/disables SSL certificate verification. Useful for environments where the proxy is unreliable with HTTPS connections. Boolean: `true` or `false`. | `True` |
+| `QDT_PAC_FILE` | Define PAC file for proxy definition. See also [How to use behind a proxy](../guides/howto_behind_proxy.md). | `` |
 
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