Rename to "content-address*ing* derivation"

"content-address*ed*" derivation is misleading because all derivations
are *themselves* content-addressed. What may or may not be
content-addressed is not derivation itself, but the *output* of the
derivation.

The outputs are not *part* of the derivation (for then the derivation
wouldn't be complete before we built it) but rather separate entities
produced by the derivation.

"content-adddress*ed*" is not correctly because it can only describe
what the derivation *is*, and that is not what we are trying to do.

"content-address*ing*" is correct because it describes what the
derivation *does* --- it produces content-addressed data.

src/libstore/unix/build/local-derivation-goal.cc

@@ -800,7 +800,7 @@ void LocalDerivationGoal::startBuilder()
            out. */
         for (auto & i : drv->outputsAndOptPaths(worker.store)) {
             /* If the name isn't known a priori (i.e. floating
-               content-addressed derivation), the temporary location we use
+               content-addressing derivation), the temporary location we use
                should be fresh.  Freshness means it is impossible that the path
                is already in the sandbox, so we don't need to worry about
                removing it.  */
@@ -2291,7 +2291,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
        to do anything here.
 
        We can only early return when the outputs are known a priori. For
-       floating content-addressed derivations this isn't the case.
+       floating content-addressing derivations this isn't the case.
      */
     if (hook)
         return DerivationGoal::registerOutputs();

src/libstore/unix/build/local-derivation-goal.hh

@@ -130,7 +130,7 @@ struct LocalDerivationGoal : public DerivationGoal
      *   rewrite after the build. Otherwise the regular predetermined paths are
      *   put here.
      *
-     * - Floating content-addressed derivations do not know their final build
+     * - Floating content-addressing derivations do not know their final build
      *   output paths until the outputs are hashed, so random locations are
      *   used, and then renamed. The randomness helps guard against hidden
      *   self-references.