Add another link for panic strategy

Author: ehuss

src/conditional-compilation.md

@@ -304,14 +304,16 @@ r[cfg.panic]
 ### `panic`
 
 r[cfg.panic.general]
-Key-value option set depending on the panic strategy. Note that more values may be added in the future.
+Key-value option set depending on the [panic strategy]. Note that more values may be added in the future.
 
 r[cfg.panic.values]
 Example values:
 
 * `"abort"`
 * `"unwind"`
 
+[panic strategy]: panic.md#panic-strategy
+
 ## Forms of conditional compilation
 
 r[cfg.attr]