Extend instructions in READMEs (#951)

README.md

@@ -125,7 +125,8 @@ See the `Makefile`s and `Dockerfile`s, as well as [build/alpine/README.md](build
 
 ### How to run integration tests
 
-Integration tests require all of the haskell services (brig, galley, cannon, gundeck, proxy, cargohold, spar) to be correctly configured and running, before being able to execute e.g. the `brig-integration` binary. This requires most of the deployment dependencies as seen in the architecture diagram to also be available:
+Integration tests require all of the haskell services (brig, galley, cannon, gundeck, proxy, cargohold, spar) to be correctly configured and running, before being able to execute e.g. the `brig-integration` binary. The test for brig also starts nginz, so make sure it has been built before.
+These services require most of the deployment dependencies as seen in the architecture diagram to also be available:
 
 - Required internal dependencies:
     - cassandra (with the correct schema)

libs/libzauth/README.md

@@ -2,7 +2,7 @@
 
 ## Compile and install natively
 
-To build libzauth natively, you will need to have the usual C compiler toolchains installed.
+To build libzauth natively, you will need to have the usual C compiler toolchains installed, as well as a Rust toolchain (i.e. through [rustup](https://rustup.rs/)).
 
 ### Ubuntu / Debian
 

services/nginz/README.md

@@ -20,9 +20,11 @@ _Note_: Debian packages are only used as part of wire's infrastructure, and as s
 
 _Note_: Debian stable does not contain a new enough version of libsodium. you must get it from backports, testing, or unstable.
 
+_Note_: On some Ubuntu versions, upstart is installed in addition to systemd, causing runit to fail with an error like "Unable to connect to Upstart: Failed to connect to socket". Luckily, there is [a simple fix](https://forum.peppermintos.com/index.php?topic=5210.0).
+
 #### Build Dependencies:
 ```bash
-sudo apt install libossp-uuid-dev libpcre3-dev libsodium23 runit
+sudo apt install libossp-uuid-dev libpcre3-dev libsodium23 runit gnupg
 ```
 
 #### Building