docs: update README

Author: bushidocodes

README.md

@@ -24,4 +24,33 @@ ARGS:
     <input>    Input wasm file
 
 ```
-Relies on you having a sensible llvm toolchain on your computer (so we can call llvm-config)
+
+# Installation from Source
+
+## Debian-based Systems
+```sh
+git clone https://github.com/gwsystems/silverfish.git
+cd silverfish
+./install_deb.sh
+```
+
+The compiler can now be run via `silverfish`
+
+## Others
+1. [Install Rust](https://www.rust-lang.org/tools/install)
+2. [Install LLVM](http://releases.llvm.org/download.html)
+3. Link Your Clang Installation so `clang-9` and `llvm-config-9` are in your path and invokable as `clang` and `llvm-config`. For example, the following commands accomplish this using `update-alternatives` after replacing LLVM_VERSION with the version returned you installed above (In *NIX systems, this can be confirmed with `ls /usr/bin/clang*`)
+```sh
+LLVM_VERSION=9
+sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-$LLVM_VERSION 100
+sudo update-alternatives --install /usr/bin/llvm-config llvm-config /usr/bin/llvm-config-$LLVM_VERSION 100
+```
+4. [Install the C++ Standard Library for LLVM](https://libcxx.llvm.org/)
+​
+5. Clone and build silverfish
+```sh
+git clone https://github.com/gwsystems/silverfish.git
+cd silverfish
+cargo build --release
+```
+6. The silverfish binary is built at `target/release/silverfish`. Copy this to the appropriaate place for your platform and add to your PATH if neccessary.