Add documentation.

Author: nochiel

packaging.md

@@ -0,0 +1,21 @@
+# How to build a Debian package.
+
+If you can read this file, you should be in a checked-out `debian/latest` branch.
+
+0. Apply the patches listed in `debian/patches/series`. They should apply cleanly before the repository can be compiled.
+```sh
+cat debian/series | xargs -I{} patch --strip=1 -i "debian/patches/{}"
+```
+Or
+
+```sh
+while read -r f; do
+    patch -i "debian/patches/$f"
+done < debian/series
+```
+
+In order to compile Sweeptool on Debian, [OpenSSL 1.1.1](https://www.openssl.org/source/openssl-1.1.1t.tar.gz) is required. After downloading and compiling it, compile sweeptool with a command in the form: 
+7
+```sh
+OPENSSL_DIR=$HOME/wip/openssl-1.1.1t OPENSSL_LIB_DIR=$HOME/wip/openssl-1.1.1t cargo build
+```