Fix comments in specialization id example

Some of the comments for this example were accidentally deleted when
running clang-format in 8a54f69.  Fix
them.

We can also pack more words on each line since clang-format reduced
the indentation.

Author: gmlueck

adoc/code/specialization_id.cpp

@@ -41,12 +41,11 @@ namespace {
 constexpr specialization_id<int> same_name { 12 }; // OK
 }
 inline namespace other {
-int same_name; // ILLEGAL: shadows "specialization_id"
-               // variable with same name in enclosing
-               // namespace scope
+int same_name; // ILLEGAL: shadows "specialization_id" variable with same name in
+               // enclosing namespace scope
 }
 inline namespace {
-namespace foo { // ILLEGAL: namespace name shadows "::foo"
+namespace foo { // ILLEGAL: namespace name shadows "::foo" namespace which contains
+                // "specialization_id" variable.
 } // namespace foo
-  // "specialization_id" variable.
 } // namespace