Add preliminary syntax information to the Readme.

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

README.md

@@ -1,3 +1,54 @@
 # ELox
 
-A partial Lox implementation for embedded devices.
+A Lox variant for embedded devices.
+It's sole purpose is to be a playground to implement an
+end to end compiler for embedded devices.
+
+## Features
+
+ELox omits some features from Lox and borrows some others from C.
+The feature set is meant to be restrictive to ease implementation.
+
+- Static typing with no type inference.
+- Words (`word`), and boolean (`true` and `false`) types.
+- Word literals in different formats: `101`, `0x101`, `0b101`, `0o101`.
+- Arithmetic expressions: `+`, `-`, `*`, `<<`, `>>`.
+- Logical expressions: `&&`, `||`, `==`, `!=`, `<`, `<=`, `>`, `>=`.
+- Bitwise expressions: `&`, `|`, `^`.
+- Stack and global variables: `var myWord word`.
+- Control flow with `if`, `while` and `for` with usual C-like syntax.
+- Memory regions which can be used to access a group of registers more effectively.
+  They must be instantiated at a particular address and all elements are words.
+  ```
+  mem someRegGroup {
+    reg1
+    reg2
+    reg3
+  }
+
+  var regs someRegGroup = @0xdfffffff
+
+  fun main () {
+    regs.reg1 = 0xff
+    var test word = regs.reg2
+  }
+  ```
+- Functions
+  ```
+  // This is a comment btw.
+  fun myFunWithReturn(arg1 word, arg2 bool) word {
+    var res word = 0
+    if (arg2) {
+        res = arg1
+    } else {
+        res = arg1 * arg1
+    }
+  }
+
+  fun myFun(arg1 word, arg2 word) {
+    doSomethingElse(arg1, arg2)
+  }
+  ```
+
+Notable ommisions are signed integers, heap variables (no malloc implementation yet),
+arrays, structs and strings. These may be slowly implemented as needs arise.