Updated MISRA entry with link, updating PR #1554

Author: hsutter

CppCoreGuidelines.md

@@ -20417,7 +20417,7 @@ Reference sections:
   Libraries used have to have been approved for mission critical applications.
   Any similarities to this set of guidelines are unsurprising because Bjarne Stroustrup was an author of JSF++.
   Recommended, but note its very specific focus.
-* _MISRA C++ 2008: Guidelines for the use of the C++ language in critical systems_. (Copies of this document can be found on the Internet, but it is not clear whether they are legally posted. This may limit its usefulness.)
+* [_MISRA C++ 2008: Guidelines for the use of the C++ language in critical systems_] (https://www.misra.org.uk/Buyonline/tabid/58/Default.aspx).
 * [Mozilla Portability Guide](https://developer.mozilla.org/en-US/docs/Mozilla/C%2B%2B_Portability_Guide).
   As the name indicates, this aims for portability across many (old) compilers.
   As such, it is restrictive.