Reducing the amount of "items" in the root of the repo

by moving documents into a own docs directory.

docs/HACKING.md

@@ -0,0 +1,37 @@
+# Readme for hacking on the source
+
+## Build systems
+The build system of I2P today is a bit mixed. 
+In the old days, and at least for relasing we actually use
+the old `ant` tool. For the new Browser Bundle launcher, as 
+well as the Mac OSX launcher the `sbt` tool from the Scala 
+world was used cause it gives some increadibly effictive plugins
+and logic to build them while keeping a relation to the old build 
+system.
+
+We also have Gradle partly implemented, much work, but not all. Meeh 
+which is writing this readme is guessing we'll end up with a combination
+of Gradle and SBT in the end when we know what kind of structure we want.
+
+
+## Browsing around the source code
+
+If you're new at this, which we all was at one point, I'll have some tips.
+
+* Check out our [DIRECTORIES.md](DIRECTORIES.md) to learn ore 
+about where you'll find I2P's different parts in the codebase.
+
+* For me (Meeh), it worked well to run `find . -type f -name '*Runner.java'` 
+from the source tree root, and take a look at the files that get listed. A lot 
+of hints of how this is peaced together lies there.
+
+
+## The .. Monotone part
+
+Check out [MONOTONECHEATSHEET.md](MONOTONECHEATSHEET.md) file.
+
+## SBT Behind proxy
+
+Seems it's a hassle behind SOCKSv5. But for use of HTTP proxy to fetch 
+dependencies and such, please edit `export SBT_OPTS="$SBT_OPTS -Dhttp.proxyHost=myproxy-Dhttp.proxyPort=myport"` 
+to have correct values for your system, then execute it before you start SBT.