Update installation instructions

Author: ubruhin

modules/installation/pages/build-from-sources.adoc

@@ -6,24 +6,17 @@
 
 To compile LibrePCB, you need to install the following tools & libraries first:
 
-* pass:[g++], MinGW or Clang (any version with pass:[C++17] support should work)
+* pass:[g++], MinGW or Clang (any version with pass:[C++20] support should work)
+* https://www.rust-lang.org/[Rust] >= 1.88 toolchain (GNU, not MSVC)
 * http://www.qt.io/download-open-source/[Qt] >= 6.2 (make sure the
   https://doc.qt.io/qt-6/qtimageformats-index.html[imageformats] plugin
   is installed too as it will be needed at runtime)
 * https://www.opencascade.com/[OpenCASCADE] OCCT or OCE (optional, OCCT
   highly preferred)
 * https://en.wikipedia.org/wiki/OpenGL_Utility_Library[OpenGL Utility Library]
   GLU (optional)
-* http://www.zlib.net/[zlib]
 * https://www.openssl.org/[OpenSSL]
-* https://cmake.org/[CMake] 3.16 or newer
-
-[IMPORTANT]
-====
-Actually LibrePCB 1.2.0 still compiles with Qt5, but unfortunately contains a
-serious bug at runtime. Therefore you really need to use Qt6 where the bug
-doesn't exist. We'll drop support for Qt5 soon anyway.
-====
+* https://cmake.org/[CMake] 3.22 or newer
 
 == Get the Sources
 

modules/installation/pages/windows.adoc

@@ -11,15 +11,6 @@ The recommended way to install LibrePCB is to use the installer.
 *Just download and run {installer-url}[{installer-filename}].*
 Afterwards you'll find LibrePCB in your start menu.
 
-[IMPORTANT]
-====
-Unfortunately we're not able yet to sign our Windows installer (it's quite
-expensive to do it). Therefore Windows might warn that the publisher of the
-installer is unknown. This is normal for binaries without paying for a
-signature, therefore just click on btn:[More info] and then btn:[Run anyway]
-to skip the warning.
-====
-
 [NOTE]
 ====
 For automated (unattended) installation, please check out the command-line