Documentation updates.

Author: arbv

README.md

@@ -4,7 +4,7 @@ This library provides a low-level facility for context switching between multipl
 
 The low level context switching facility consists of a data type (`avr_context_t`), functions (`avr_getcontext()`, `avr_setcontext()`, `avr_makecontext()`, `avr_swapcontext()`), and macros (`AVR_SAVE_CONTEXT`, `AVR_RESTORE_CONTEXT`, `AVR_SAVE_CONTEXT_GLOBAL_POINTER`, `AVR_RESTORE_CONTEXT_GLOBAL_POINTER`). It is safe to say that this facility provifes implementations (or, rather, substitutes) for `getcontext()`, `setcontext()`, `makecontext()`, and `swapcontext()` which are available on the UNIX-like systems.
 
-The asymmetric stackful coroutines facility consists of a data type (`avr_corot_t`), and four functions (`avr_coro_init()`, `avr_coro_resume()`, `avr_coro_yield()`, `avr_coro_state()`). This functionality is implemented on top of the context switching facility.
+The asymmetric stackful coroutines facility consists of a data type (`avr_corot_t`), and four functions (`avr_coro_init()`, `avr_coro_resume()`, `avr_coro_yield()`, `avr_coro_state()`). This functionality is implemented on top of the context switching facility. This facility semantics closely follows the semantics of asymmetric stackful coroutines described in the paper ["Ana Lucia De Moura, Roberto Ierusalimschy - Revisiting Coroutines"](http://www.inf.puc-rio.br/~roberto/docs/MCC15-04.pdf).
 
 One can use the provided functionality in many creative ways. For example, on top of this one can implement:
 
@@ -438,6 +438,7 @@ Consumed: 10
 4. [The Open Group Base Specifications Issue 6: getcontext, setcontext - get and set current user context](https://pubs.opengroup.org/onlinepubs/009695399/functions/getcontext.html)
 5. [The Open Group Base Specifications Issue 6: makecontext, swapcontext - manipulate user contexts](https://pubs.opengroup.org/onlinepubs/009695399/functions/makecontext.html)
 6. [Ana Lucia De Moura, Roberto Ierusalimschy - Revisiting Coroutines, ACM Transactions on Programming Languages and Systems 31(2), July 2004](http://www.inf.puc-rio.br/~roberto/docs/MCC15-04.pdf)
+7. [AVR-GCC: Application Binary Interface](https://gcc.gnu.org/wiki/avr-gcc)
 
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