[1177] fixed a few minor typo directly.

src/lib/datasrc/database.cc

@@ -308,7 +308,7 @@ namespace {
 // convenient.
 //
 // While this is not straightforward use of the + operator, some mathematical
-// conventions do allow summing sets with elements (usually in communitative
+// conventions do allow summing sets with elements (usually in commutative
 // way, we define only one order of the operator parameters, as the other
 // isn't used).
 //

src/lib/datasrc/database.h

@@ -659,7 +659,7 @@ public:
          * \param name Which domain name should be scanned.
          * \param types List of types the caller is interested in.
          * \param check_ns If this is set to true, it checks nothing lives
-         *     together with NS record (with few little exceptions, like RRSET
+         *     together with NS record (with few little exceptions, like RRSIG
          *     or NSEC). This check is meant for non-apex NS records.
          * \param construct_name If this is NULL, the resulting RRsets have
          *     their name set to name. If it is not NULL, it overrides the name