docs: update env-example

.env-example

@@ -1,11 +1,12 @@
 # app settings
 HOST=0.0.0.0
+# HOST=127.0.0.1
 PORT=8080
-DASH_DEBUG=False
+# DASH_DEBUG=True
 
 # available corpora
 CORPORA_YML="config/corpora-ske.yml"
-# corpora summary
+# corpora summary (optional)
 CORPORA_MD="config/corpora.md"
 
 # maximum CQL rules searched for simultaneously
@@ -20,14 +21,14 @@ SGEX_USERNAME="<USER>"
 SGEX_SERVER=ske
 # or any other server
 # SGEX_SERVER=https://api.sketchengine.eu/bonito/run.cgi
-# threading only works with localhost servers
+# threading (async API calling; only works with localhost servers)
 # SGEX_THREAD=True
-# for inspecting stdout
+# API request verbosity
 # SGEX_VERBOSE=True
-# custom call throttling times (see sgex package docs)
+# custom call throttling times (see sgex Python package docs)
 # SGEX_WAIT_DICT="<{JSON_DICT}>"
 
-# URL for generating external links
+# URL for generating external links (optional)
 # SERVER_URL=https://app.sketchengine.eu
 
 # docker