Add other requirements for building to main README

The "other requirements" are listed in the [reproducible builds readme](https://github.com/sparrowwallet/sparrow/blob/master/docs/reproducible.md#other-requirements) already. However when trying to quickly build the binaries and follow the main README instructions, the last paragraph about "[m]ore detailed instructions on reproducing the binaries are provided" can be overlooked very easily. Because the paragraph is about the specific topic "reproducible builds" and not building the binaries from source in general.

README.md

@@ -19,7 +19,12 @@ or for those without SSH credentials:
 In order to build, Sparrow requires Java 16 to be installed. 
 The release binaries are built with [AdoptOpenJdk 16.0.1+9 Hotspot](https://adoptopenjdk.net/archive.html?variant=openjdk16&jvmVariant=hotspot).
 
-These binaries can be built from source using
+Other packages may also be necessary to build depending on the platform. On Debian/Ubuntu systems:
+
+`sudo apt install -y rpm fakeroot binutils`
+
+
+The Sparrow binaries can be built from source using
 
 `./gradlew jpackage`