docs: Update to use Make for source builds, recommend built tarballs as a primary way

docs/tutorials/building-from-source.md

@@ -0,0 +1,47 @@
+# Building from source
+
+## System dependencies
+
+You need C toolchain, Go toolchain and Make:
+
+On Debian-based system this should work:
+```
+apt-get install golang-1.14 gcc libc6-dev make
+```
+
+Additionally, if you want manual pages, you should also have scdoc installed.
+Figuring out the appropriate way to get scdoc is left as an exercise for
+reader (for Ubuntu 19.10 it is in repositories).
+
+## Recent Go toolchain
+
+maddy depends on a rather recent Go toolchain version that may not be
+available in some distributions (*cough* Debian *cough*).
+
+It should not be hard to grab a recent built toolchain from golang.org:
+```
+wget "https://dl.google.com/go/go1.14.6.linux-amd64.tar.gz"
+tar xf "go1.14.6.linux-amd64.tar.gz"
+export GOROOT="$PWD/go"
+export PATH="$PWD/go/bin:$PATH"
+```
+
+## Step-by-step
+
+1. Clone repository
+```
+git clone https://github.com/foxcpp/maddy.git
+cd maddy
+```
+
+2. Build it
+```
+make
+```
+
+3. Install it
+```
+sudo make install
+```
+
+Have fun!