CLI Improvements (#1021)

* Add gpt4all-bindings/cli/README.md

* Unify version information
- Was previously split; base one on the other
- Add VERSION_INFO as the "source of truth":
  - Modelled after sys.version_info.
  - Implemented as a tuple, because it's much easier for (partial)
    programmatic comparison.
- Previous API is kept intact.

* Add gpt4all-bindings/cli/developer_notes.md
- A few notes on what's what, especially regarding docs

* Add gpt4all-bindings/python/docs/gpt4all_cli.md
- The CLI user documentation

* Bump CLI version to 0.3.5

* Finalise docs & add to index.md
- Amend where necessary
- Fix typo in gpt4all_cli.md
- Mention and add link to CLI doc in index.md

* Add docstings to gpt4all-bindings/cli/app.py

* Better 'groovy' link & fix typo
- Documentation: point to the Hugging Face model card for 'groovy'
- Correct typo in app.py

gpt4all-bindings/cli/app.py

@@ -1,9 +1,17 @@
+"""GPT4All CLI
+
+The GPT4All CLI is a self-contained script based on the `gpt4all` and `typer` packages. It offers a
+REPL to communicate with a language model similar to the chat GUI application, but more basic.
+"""
+
 import sys
 import typer
 
+from collections import namedtuple
 from typing_extensions import Annotated
 from gpt4all import GPT4All
 
+
 MESSAGES = [
     {"role": "system", "content": "You are a helpful assistant."},
     {"role": "user", "content": "Hello there."},
@@ -17,7 +25,9 @@ SPECIAL_COMMANDS = {
     "/help": lambda _: print("Special commands: /reset, /exit, /help and /clear"),
 }
 
-VERSION = "0.3.4"
+VersionInfo = namedtuple('VersionInfo', ['major', 'minor', 'micro'])
+VERSION_INFO = VersionInfo(0, 3, 5)
+VERSION = '.'.join(map(str, VERSION_INFO))  # convert to string form, like: '1.2.3'
 
 CLI_START_MESSAGE = f"""
     
@@ -47,6 +57,7 @@ def repl(
         typer.Option("--n-threads", "-t", help="Number of threads to use for chatbot"),
     ] = None,
 ):
+    """The CLI read-eval-print loop."""
     gpt4all_instance = GPT4All(model)
 
     # if threads are passed, set them
@@ -103,7 +114,8 @@ def repl(
 
 @app.command()
 def version():
-    print("gpt4all-cli v0.3.4")
+    """The CLI version command."""
+    print(f"gpt4all-cli v{VERSION}")
 
 
 if __name__ == "__main__":