docs/building.md: add docs for building Kilo and the website (#177)

* docs/building.md: add docs for building Kilo and the website

Signed-off-by: leonnicolas <leonloechner@gmx.de>

Update docs/building_kilo.md

Co-authored-by: Lucas Servén Marín <lserven@gmail.com>

* Apply suggestions from code review

Co-authored-by: Lucas Servén Marín <lserven@gmail.com>

Co-authored-by: Lucas Servén Marín <lserven@gmail.com>

docs/building_kilo.md

@@ -0,0 +1,100 @@
+# Build and Test Kilo
+
+This document describes how you can build and test Kilo.
+
+To follow along, you need to install the following utilities:
+ - `go` not for building but formatting the code and running unit tests
+ - `make`
+ - `jq`
+ - `git`
+ - `curl`
+ - `docker`
+
+## Getting Started
+
+Clone the Repository and `cd` into it.
+```shell
+git clone https://github.com/squat/kilo.git
+cd kilo
+```
+
+## Build
+
+For consistency, the Kilo binaries are compiled in a Docker container, so make sure the `docker` package is installed and the daemon is running.
+
+### Compile Binaries
+
+To compile the `kg` and `kgctl` binaries run:
+```shell
+make
+```
+Binaries are always placed in a directory corresponding to the local system's OS and architecture following the pattern `bin/<os>/<architecture>/`, so on an AMD64 machine running Linux, the binaries will be stored in `bin/linux/amd64/`.
+
+You can build the binaries for a different architecture by setting the `ARCH` environment variable before invoking `make`, e.g.:
+```shell
+ARCH=<arm|arm64|amd64> make
+```
+
+Likewise, to build `kg` for another OS, set the `OS` environment variable before invoking `make`:
+```shell
+OS=<windows|darwin|linux> make
+```
+## Test
+
+To execute the unit tests, run:
+```shell
+make unit
+```
+
+To lint the code in the repository, run:
+```shell
+make lint
+```
+
+To execute basic end to end tests, run:
+```shell
+make e2e
+```
+__Note__: The end to end tests are currently flaky, so try running them again if they fail.
+
+To instead run all of the tests with a single command, run:
+```shell
+make test
+```
+
+## Build and Push the Container Images
+
+If you want to build containers for a processor architecture that is different from your computer's, then you will first need to configure QEMU as the interpreter for binaries built for non-native architectures:
+```shell
+docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
+```
+
+Set the `$IMAGE` environment variable to `<your Docker Hub user name>/kilo`.
+This way the generated container images and manifests will be named accordingly.
+By skipping this step, you will be able to tag images but will not be able to push the containers and manifests to your own Docker Hub.
+```shell
+export IMAGE=<docker hub user name>/kilo
+```
+
+If you want to use a different container registry, run:
+```shell
+export REGISTRY=<your registry without a trailing slash>
+```
+
+To build containers with the `kg` image for `arm`, `arm64` and `amd64`, run:
+```shell
+make all-container
+```
+
+Push the container images and build a manifest with:
+```shell
+make manifest
+```
+
+To tag and push the manifest with `latest`, run:
+```shell
+make manifest-latest
+```
+
+Now you can deploy the custom build of Kilo to your cluster.
+If you are already running Kilo, change the image from `squat/kilo` to `[registry/]<username>/kilo[:sha]`.