address PR review comments on api docs

docs/changelog.txt

@@ -51,7 +51,7 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 - `confirm`: added a confirmation dialog for convicting dwarves of crimes
 
 ## API
-- Added ``Filesystem::mkdir_recursive`` (returns true if directories to create already exist)
+- Added ``Filesystem::mkdir_recursive``
 - Extended ``Filesystem::listdir_recursive`` to optionally make returned filenames relative to the start directory
 
 ## Lua

library/include/modules/Filesystem.h

@@ -149,6 +149,7 @@ namespace DFHack {
         DFHACK_EXPORT bool chdir (std::string path);
         DFHACK_EXPORT std::string getcwd ();
         DFHACK_EXPORT bool mkdir (std::string path);
+        // returns true on success or if directory already exists
         DFHACK_EXPORT bool mkdir_recursive (std::string path);
         DFHACK_EXPORT bool rmdir (std::string path);
         DFHACK_EXPORT bool stat (std::string path, STAT_STRUCT &info);
@@ -160,6 +161,8 @@ namespace DFHack {
         DFHACK_EXPORT int64_t ctime (std::string path);
         DFHACK_EXPORT int64_t mtime (std::string path);
         DFHACK_EXPORT int listdir (std::string dir, std::vector<std::string> &files);
+        // set include_prefix to false to prevent dir from being prepended to
+        // paths returned in files
         DFHACK_EXPORT int listdir_recursive (std::string dir, std::map<std::string, bool> &files,
             int depth = 10, bool include_prefix = true);
     }