Add Getting started section to README (#513)

README.md

@@ -56,16 +56,24 @@ Run `shards --help` to list other commands with their options.
 
 Happy Hacking!
 
+## Developers
 
-## Requirements
+### Requirements
 
-These requirements are only for compiling Shards.
+These requirements are only necessary for compiling Shards.
 
 * Crystal
 
   Please refer to <https://crystal-lang.org/install/> for
   instructions for your operating system.
 
+* `molinillo`
+
+  The shard `molinillo` needs to be in the Crystal path.
+  It is available at <https://github.com/crystal-lang/crystal-molinillo>
+  You can install it either with a pre-existing `shards` binary (running `shards install`)
+  or just check out the repository at `lib/crystal-molinillo` (`make lib`).
+
 * libyaml
 
   On Debian/Ubuntu Linux you may install the `libyaml-dev` package.
@@ -79,6 +87,25 @@ These requirements are only for compiling Shards.
 
   Needed for building manpages.
 
+### Getting started
+
+It is strongly recommended to use `make` for building shards and developing it.
+The [`Makefile`](./Makefile) contains recipes for compiling and testing. Building
+with `make` also ensures the source dependency `molinillo` is installed. You don't
+need to take care of this yourself.
+
+Run `make bin/shards` to build the binary.
+* `release=1` for a release build (applies optimizations)
+* `static=1` for static linking (only works with musl-libc)
+* `debug=1` for full symbolic debug info
+
+Run `make install` to install the binary. Target path can be adjusted with `PREFIX` (default: `PREFIX=/usr/bin`).
+
+Run `make test` to run the test suites:
+* `make test_unit` runs unit tests (`./spec/unit`)
+* `make test_integration` runs integration tests (`./spec/integration`) on `bin/shards`
+
+Run `make docs` to build the manpages.
 
 ## License