server : update readme about token probs (ggerganov#4777)

* updated server readme to reflect the gg/server-token-probs-4088 commit

added explanation for the API's completion result which now includes `completion_probabilities`. Also added a JSON schema that shows the type/structure of `completion_probabilities`.

* simplified the `completion_probabilities` JSON schema 

It's now easier to understand what the structure of `completion_probabilities` looks like.

* minor : fix trailing whitespace

---------

Co-authored-by: Georgi Gerganov <[email protected]>

examples/server/README.md

@@ -175,35 +175,44 @@ node index.js
 
     `system_prompt`: Change the system prompt (initial prompt of all slots), this is useful for chat applications. [See more](#change-system-prompt-on-runtime)
 
-    *Result JSON:*
+### Result JSON:
 
-    Note: When using streaming mode (`stream`) only `content` and `stop` will be returned until end of completion.
+* Note: When using streaming mode (`stream`) only `content` and `stop` will be returned until end of completion.
 
-    `content`: Completion result as a string (excluding `stopping_word` if any). In case of streaming mode, will contain the next token as a string.
 
-    `stop`: Boolean for use with `stream` to check whether the generation has stopped (Note: This is not related to stopping words array `stop` from input options)
+- `completion_probabilities`: An array of token probabilities for each completion. The array's length is `n_predict`. Each item in the array has the following structure:
 
-    `generation_settings`: The provided options above excluding `prompt` but including `n_ctx`, `model`
-
-    `model`: The path to the model loaded with `-m`
-
-    `prompt`: The provided `prompt`
-
-    `stopped_eos`: Indicating whether the completion has stopped because it encountered the EOS token
-
-    `stopped_limit`: Indicating whether the completion stopped because `n_predict` tokens were generated before stop words or EOS was encountered
-
-    `stopped_word`: Indicating whether the completion stopped due to encountering a stopping word from `stop` JSON array provided
-
-    `stopping_word`: The stopping word encountered which stopped the generation (or "" if not stopped due to a stopping word)
-
-    `timings`: Hash of timing information about the completion such as the number of tokens `predicted_per_second`
-
-    `tokens_cached`: Number of tokens from the prompt which could be re-used from previous completion (`n_past`)
-
-    `tokens_evaluated`: Number of tokens evaluated in total from the prompt
-
-    `truncated`: Boolean indicating if the context size was exceeded during generation, i.e. the number of tokens provided in the prompt (`tokens_evaluated`) plus tokens generated (`tokens predicted`) exceeded the context size (`n_ctx`)
+```
+{
+  "content": "<the token selected by the model>",
+  "probs": [
+    {
+      "prob": float,
+      "tok_str": "<most likely token>"
+    },
+    {
+      "prob": float,
+      "tok_str": "<second most likely tonen>"
+    },
+    ...
+  ]
+},
+```
+Notice that each `probs` is an array of length `n_probs`.
+
+- `content`: Completion result as a string (excluding `stopping_word` if any). In case of streaming mode, will contain the next token as a string.
+- `stop`: Boolean for use with `stream` to check whether the generation has stopped (Note: This is not related to stopping words array `stop` from input options)
+- `generation_settings`: The provided options above excluding `prompt` but including `n_ctx`, `model`
+- `model`: The path to the model loaded with `-m`
+- `prompt`: The provided `prompt`
+- `stopped_eos`: Indicating whether the completion has stopped because it encountered the EOS token
+- `stopped_limit`: Indicating whether the completion stopped because `n_predict` tokens were generated before stop words or EOS was encountered
+- `stopped_word`: Indicating whether the completion stopped due to encountering a stopping word from `stop` JSON array provided
+- `stopping_word`: The stopping word encountered which stopped the generation (or "" if not stopped due to a stopping word)
+- `timings`: Hash of timing information about the completion such as the number of tokens `predicted_per_second`
+- `tokens_cached`: Number of tokens from the prompt which could be re-used from previous completion (`n_past`)
+- `tokens_evaluated`: Number of tokens evaluated in total from the prompt
+- `truncated`: Boolean indicating if the context size was exceeded during generation, i.e. the number of tokens provided in the prompt (`tokens_evaluated`) plus tokens generated (`tokens predicted`) exceeded the context size (`n_ctx`)
 
 -   **POST** `/tokenize`: Tokenize a given text.