Move the experimental building part to the BUILDING.md

Signed-off-by: Silvin Lubecki <silvin.lubecki@docker.com>

Author: silvin-lubecki

BUILDING.md

@@ -59,6 +59,16 @@ make test-e2e                   # run the end-to-end tests
 Vendoring of external imports uses the [`dep`](https://github.com/golang/dep) tool.
 Please refer to its documentation if you need to update a dependency.
 
+### Experimental
+
+Just add the `EXPERIMENTAL=on` flag before invoking a build target:
+```console
+$ make EXPERIMEMTAL=on bin/docker-app
+$ ./bin/docker-app version
+...
+Experimental: on
+```
+
 ## Build using Docker
 
 If you don't have Go installed but Docker is present, you can also use

README.md

@@ -233,6 +233,7 @@ We have lots of ideas for making Compose-based applications easier to share and
 * Saving required images into the application artifact to support offline installation
 * Signing applications with notary
 
+If you're interested in contributing to the project, jump to [BUILDING.md](BUILDING.md) and [CONTRIBUTING.md](CONTRIBUTING.md).
 
 ## Usage
 
@@ -300,11 +301,4 @@ source <(docker-app completion zsh)
 
 Some commands are flagged as experimental and will remain in this state until they mature. These commands are only accessible using an experimental binary. Feel free to test these commands and give us some feedback!
 
-### How to build your own experimental binary
-
-```console
-$ make EXPERIMEMTAL=on bin/docker-app
-$ ./bin/docker-app version
-...
-Experimental: on
-```
+See [BUILDING.md/Experimental](BUILDING.md#experimental).