* reorganize docs in build-notes*.md

docs/building/requirements.md

@@ -0,0 +1,14 @@
+Build requirements
+==================
+
+In general, for building i2pd you need several things:
+
+* compiler with c++11 support (for example: gcc >= 4.7, clang)
+* boost >= 1.49
+* openssl library
+* zlib library (openssl already depends on it)
+
+Optional tools:
+
+* cmake >= 2.8 (or 3.3+ if you want to use precompiled headers on windows)
+* miniupnp library (for upnp support)