docs: Add initial language spec

Signed-off-by: Ian Moffett <ian@mirocom.org>

SPEC.md

@@ -0,0 +1,34 @@
+# The Rifle specification
+
+## About Rifle
+
+The rifle programming language is a language aiming to keep optimization down to
+a minimum. It is to have a somewhat C-like syntax and seperate directive/keyword
+namespace.
+
+## Identifiers
+
+Identifiers are names that exist within the program that represent a specific
+symbol/object. If the name is prefixed with a dot '.' it is a reserved keyword
+or directive.
+
+## A simple main function
+
+```
+// Function is public
+// |   This is a function
+// |  /  Identifier
+// |  |  |      Type designator
+// |  |  |      /   Type
+// |  |  |     /  /
+// |  |  |     |  |
+// |  |  |     |  |
+.pub .f main() : u32 {
+    return 0;   // <-- Return statement
+}
+```
+
+A few things are going on here, first we declare the function
+as public (i.e., visible externally from the current file), then
+we use '.f' to denote that we are defining a function, followed by
+an identifier, a set of parenthesis and a type after the ':'.