Add that MIR_finish removes MIR program too.
## MIR program
* MIR program consists of MIR **modules**
* To start work with MIR program, you should first call API function `MIR_init`
- * API function `MIR_finish (MIR_context_t ctx)` should be called last. It frees all internal data used to work with MIR program
+ * API function `MIR_finish (MIR_context_t ctx)` should be called last. It frees all internal data used to work with MIR program and all IR (insns, functions, items, and modules) created in this context
* API function `MIR_output (MIR_context_t ctx, FILE *f)` outputs MIR textual representation of the program into given file
* API function `MIR_scan_string (MIR_context_t ctx, const char *str)` reads textual MIR representation given by a string
* API functions `MIR_write (MIR_context_t ctx, FILE *f)` and
