Update README with installation and updating info (#913)

Added installation and update instructions for releases.

README.md

@@ -34,9 +34,12 @@ Currently the following should be noted:
 Cardinal releases have official builds for Linux, macOS and Windows.  
 You can find these under https://github.com/DISTRHO/Cardinal/releases.
 
+#### Installing & Updating releases
+See our Wiki on installing official builds [Wiki/Install](https://github.com/DISTRHO/Cardinal/wiki/Install).
+There are additional notes in [BUILDING.md#installing](docs/BUILDING.md#installing)
+
 There are Linux builds for various architectures (armhf, arm64, i686, riscv64 and x86_64), macOS "universal" (arm64 + intel) and Windows 32 and 64bit builds.
 Both macOS and Windows builds have an installer.  
-Install instructions are available [here](https://github.com/DISTRHO/Cardinal/wiki/Install).
 
 Note: Neither the macOS or Windows builds are signed, so expect warnings saying they are from an "untrusted developer".
 
@@ -52,7 +55,6 @@ A GitHub account is required in order to download these builds.
 
 Basic building instructions are available in [BUILDING.md](docs/BUILDING.md).
 
-
 ## Plugin variants
 
 Cardinal provides 3 plugin variants - "main", Synth and FX.