Update development instructions

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fd"
-version = "2.0.0"
+version = "3.0.0"
 authors = ["David Peter <mail@david-peter.de>"]
 
 [dependencies]

README.md

@@ -116,5 +116,19 @@ makepkg -si
 
 ## Development
 ```bash
-cargo build --release
+git clone https://github.com/sharkdp/fd
+
+# Build
+cd fd
+cargo build
+
+# Run unit tests
+cargo test
+
+# Run integration tests
+cd tests
+bash test.sh
+
+# Install
+cargo install
 ```