Updated docs to reflect missing steps (#34)

- Cross compilations issues while make minikube image
- Added troubleshooting guide

DEVELOPER.md

@@ -56,6 +56,16 @@ $ cargo build
 $ cargo test
 ```
 
+Add standard library for the target platform:
+
+```
+rustup target add x86_64-unknown-linux-musl
+```
+To build a full cross compiler toolchain targeting musl Linux amd64, perform:
+
+```
+brew install filosottile/musl-cross/musl-cross
+```
 You can run development version of fluvio CLI:
 ```
 $ target/debug/fluvio
@@ -80,7 +90,14 @@ Please ensure local docker registry is running:
 ```
 ./dev-tools/minikube-docker.sh 
 ```
+```
+ docker run -d -p 5000:5000 --restart=always --name registry registry:2
+```
+Set the following environment variable:
 
+```
+export TARGET_CC=x86_64-linux-musl-gcc
+```
 Then build docker images for current source code:
 ```
 make minikube_image
@@ -160,6 +177,49 @@ Run end to end integration test with a multiple SPU.  For example, with 2 SPU
 ```
 ./target/debug/flv-test --local
 ```
+## Troubleshooting
+This guide helps users to solve issues they might face during the setup process. 
+
+###### Cross-compilation errors
+
+If you face cross-compilation errors while creating minikube image, for example
+
+```
+cargo build --bin spu-server --target x86_64-unknown-linux-musl
+error: linker `x86_64-linux-musl-gcc` not found
+ |
+ = note: No such file or directory (os error 2)
+error: aborting due to previous error
+error: could not compile `flv-spu`.
+```
+This is indicative that you need to add standard library for the target platform:
+
+```
+rustup target add x86_64-unknown-linux-musl
+```
+
+If it still doesn't work
+
+```
+brew install filosottile/musl-cross/musl-cross
+```
+
+Make sure you set the following environment variable
+
+```
+export TARGET_CC=x86_64-linux-musl-gcc
+```
+
+###### Connection issues
+
+If you face issues while connecting to the registry
 
+```
+Get http://localhost:5000/v2/: dial tcp [::1]:5000: connect: connection refused
+```
 
+It means your docker registry is not running
 
+```
+docker run -d -p 5000:5000 --restart=always --name registry registry:2
+```