Instruction for building middleware (#2320)

Co-authored-by: Mikhail Iudin <mayudin@anytype.io>

docs/Setup_For_Middleware.md

@@ -0,0 +1,25 @@
+# How to setup environment for building middleware
+## MacOS
+
+- Open a terminal.
+- Remove all other golang installations (`which go` should report that nothing found)
+- Make a dir for golang `mkdir -p $HOME/golang`
+- Update brew by `brew update`
+- Install from brew only a golang version mentioned here: [here](https://github.com/anytypeio/go-anytype-middleware#build-from-source)
+For example: `brew install go@1.xx`
+- Remember a golang install path (`/<path-to-golang>/go@1.xx/`) reported by brew 
+
+- If you have `~/.zprofile` file then add these lines here, else add these lines to `~/.zshrc`
+
+```
+export GOPATH=$HOME/golang
+export GOROOT=/<path-to-go>/go@1.xx/libexec 
+export PATH=$PATH:$GOPATH/bin
+export PATH=$PATH:$GOROOT/bin
+```
+- After restart of the terminal you will achieve all the variables set, 
+or you can simply load them in the current terminal window by `source ~/.zprofile` or `source ~/.zshrc`
+- Make sure you have set `ANDROID_HOME` variable in the same file
+- Install `NDK 23.2.8568313` via an Android SDK Package Manager
+
+Now you can build the middleware library for android.