updated .env.example to reflect new parameters

Author: yihao03

i18n/.env.example

@@ -1,8 +1,28 @@
 API_KEY=
-AI_MODEL=gpt-4o
-# maximum number of characters to be sent for translation per batch
-MAX_LEN=2000
-#Optional
+
+# Model to be used for translation
+# ensure that selected assistant supports file search API
+# models that are tried and shown to work includes: o3-mini, 4o and 4o mini
+AI_MODEL=gpt-4.1-nano
+
+# maximum number of characters to be sent for translation per batch, default: 3000
+# smaller number of characters could lead to greater translation quality
+# but worse continuity
+MAX_LEN=5000
+
+#Optional, only specify if calling alternative LLM provider
+# Note: We require the Assistant API which only OpenAI provides as of 13 April 2025
 AI_BASEURL=
+
 # maximum number of concurent translations that are allowed
-MAX_TRANSLATION_NO=10
+# if unspecified default to 5
+MAX_TRANSLATION_NO=10
+
+# Number of previous messages to be referred to in a thread for LLM Translation, if unspecified, default to 3
+# Higher context size might lead to greater continuity in translation but higher cost and lower speed.
+CONTEXT=3
+
+# Number of token per query which when exceeded will log an error
+# Formula to derive an adequate value: MAX_LEN * CONTEXT * k, where k is a constant
+# Recommended k = 1.5
+TOKEN_WARNING=7000