chore: drop mention of obsolete RADICLE_CI_BROKER_WEBOOT from docs

Also drop PATH from the `cib` config example in the user guide, as it's
not always necessary.

README.md

@@ -13,15 +13,12 @@ The `doc` directory holds some documentation for the Radicle CI Broker:
 * If you plan to contribute or extend `radicle-ci-broker`, checkout the [architecture document](doc/architecture.md)
 
 HTML pages can be generated from the documentation.  To build those,
-run `make` in the `doc` directory:
+run `make` in the `doc` directory.
 
 ~~~
-RADICLE_CI_BROKER_WEBROOT=/tmp/ci make -C doc publish
+make -C doc
 ~~~
 
-The `RADICLE_CI_BROKER_WEBROOT` environment variable defines where the
-generated HTML pages should end up.
-
 You'll need some tools installed: [Pandoc](https://pandoc.org),
 [graphviz](https://www.graphviz.org) (dot),
 [PlantUML](https://plantuml.com),

doc/userguide.md

@@ -211,8 +211,6 @@ adapters:
     command: /bin/radicle-ci-ambient
     env:
       RADICLE_CI_AMBIENT: /home/_rad/radicle-ci-ambient.yaml
-      RADICLE_CI_BROKER_WEBROOT: /srv/pages/ci-broker
-      PATH: /bin:/home/_rad/.radicle/bin:/home/_rad/.cargo/bin
 triggers:
   - adapter: ambient
     filters: