[core/README] Add max_workers config option

Addresses #148

README.md

@@ -469,6 +469,8 @@ Legendary supports some options as well as game specific configuration in `~/.co
 log_level = debug
 ; maximum shared memory (in MiB) to use for installation
 max_memory = 1024
+; maximum number of worker processes when downloading (fewer wokers will be slower, but also use fewer system resources)
+max_workers = 8
 ; default install directory
 install_dir = /mnt/tank/games
 ; locale override, must be in RFC 1766 format (e.g. "en-US")

legendary/core.py

@@ -792,6 +792,9 @@ class LegendaryCore:
         else:
             process_opt = False
 
+        if not max_workers:
+            max_workers = self.lgd.config.getint('Legendary', 'max_workers', fallback=0)
+
         dlm = DLManager(install_path, base_url, resume_file=resume_file, status_q=status_q,
                         max_shared_memory=max_shm * 1024 * 1024, max_workers=max_workers,
                         dl_timeout=dl_timeout)