descriptors: fix docstring (param [in] vs [out])

As in title, these docstrings look incorrect.

Author: SomberNight

src/script/descriptor.h

@@ -35,7 +35,7 @@ class DescriptorCache {
     /** Retrieve a cached parent xpub
      *
      * @param[in] key_exp_pos Position of the key expression within the descriptor
-     * @param[in] xpub The CExtPubKey to get from cache
+     * @param[out] xpub The CExtPubKey to get from cache
      */
     bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
     /** Cache an xpub derived at an index
@@ -49,7 +49,7 @@ class DescriptorCache {
      *
      * @param[in] key_exp_pos Position of the key expression within the descriptor
      * @param[in] der_index Derivation index of the xpub
-     * @param[in] xpub The CExtPubKey to get from cache
+     * @param[out] xpub The CExtPubKey to get from cache
      */
     bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const;
     /** Cache a last hardened xpub
@@ -61,7 +61,7 @@ class DescriptorCache {
     /** Retrieve a cached last hardened xpub
      *
      * @param[in] key_exp_pos Position of the key expression within the descriptor
-     * @param[in] xpub The CExtPubKey to get from cache
+     * @param[out] xpub The CExtPubKey to get from cache
      */
     bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;