Update GOVPP_CLI doc (#141)

Signed-off-by: Ondrej Fabry <[email protected]>

Author: ondrej-fabry

Diff for: docs/GOVPP_CLI.md

@@ -2,26 +2,31 @@
 
 This document provides guide for the GoVPP CLI app.
 
+---
 
-## Installation of GoVPP CLI
+## Installation
 
-### Prerequisites
+To install GoVPP CLI it is currently required to have Go installed on your system.
+
+#### Prerequisites
 
-- Go 1.19+
+- **Go** 1.19+ ([installation](https://go.dev/doc/install))
 
-### Install
+### Install with Go
 
-To install GoVPP CLI, run:
+To install from the latest GoVPP release, run:
 
 ```shell
-# Latest release
 go install go.fd.io/govpp/cmd/govpp@latest
+```
 
-# Development version
+To install the most recent development version, run: 
+
+```shell
 go install go.fd.io/govpp/cmd/govpp@master
 ```
 
-## Getting Started with the GoVPP CLI
+## Getting Started
 
 The GoVPP CLI is a powerful tool for managing your VPP API development, maintenance and integration. With features such as VPP API schema export, comparison, linting, breaking change detector, Go code bindings generation and running a proxy or HTTP service for the VPP API, the GoVPP CLI offers a comprehensive solution for the VPP API management. The GoVPP CLI is designed to integrate seamlessly with your existing workflow, so you can focus on what matters most: write _great VPP APIs_ and develop control-plane apps to use them. Whether you are working with a small, focused project or a large, complex system, the GoVPP CLI is the perfect choice. In the next few minutes, you will learn how to use the GoVPP CLI to easily execute VPP CLI commands, generate code, compare schemas, and serve VPP API as an HTTP service.
 
@@ -44,98 +49,98 @@ Let's check the version of GoVPP CLI you'll be using is up-to-date.
 govpp --version
 ```
 
+This will print the version of GoVPP CLI.
+
 ## Usage
 
-```
- _________     ___    _________________
- __  ____/_______ |  / /__  __ \__  __ \
- _  / __ _  __ \_ | / /__  /_/ /_  /_/ / 
- / /_/ / / /_/ /_ |/ / _  ____/_  ____/  
- \____/  \____/_____/  /_/     /_/      
+The `govpp` command will print the usage help for the top-level commands and their subcommands by default.
 
+```
+   ______         _    _  _____   _____     govpp v0.8.0
+  |  ____  _____   \  /  |_____] |_____]    user@machine (go1.20 linux/amd64)
+  |_____| [_____]   \/   |       |          Mon Jul  3 12:13:24 CEST 2023
+                                          
 Usage:
   govpp [command]
-
+  
 Available Commands:
-  cli         Send VPP CLI command
-  diff        Compare two schemas
-  export      Export files to output location
-  generate    Generate code bindings
-  http        Serve VPP API as HTTP service
-  lint        Lint VPP API files
-  vppapi      Print VPP API
+  cli         Send CLI via VPP API
+  generate    Generate code
+  help        Help about any command
+  http        VPP API as HTTP service
+  vppapi      Manage VPP API
 
 Flags:
   -D, --debug             Enable debug mode
   -L, --loglevel string   Set logging level
       --color string      Color mode; auto/always/never
-  -v, --version           version for govpp
+      --version           version for govpp
 
 Use "govpp [command] --help" for more information about a command.
 ```
 
-### Print VPP API contents
+### Show VPP API contents
 
-The `vppapi` command allows you to print the VPP API files and their specific contents
+The `vppapi ls` command allows you to print the VPP API files and their specific contents
 in various formats. This can be useful for debugging or for generating documentation.
 
-Here's an example usage of the `vppapi` command:
+Here's an example usage of the `vppapi ls` command:
 
 ```sh
-# List VPP API files for installed VPP
-govpp vppapi
+# List VPP API files for default input
+govpp vppapi ls
 ```
 
 You can use the `--input` flag to specify the input source for the VPP API files.
 
 ```sh
 # Use current directory as input source (local VPP repository)
-govpp vppapi --input="."
+govpp vppapi ls .
 ```
 
 The default format prints the output data in a table, but you can also specify 
 other output formats such as JSON, YAML or Go template using the `--format` flag.
 
 ```sh
-# Print in common formats
-govpp vppapi --format="json"
-govpp vppapi --format="yaml"
+# Print using common formats
+govpp vppapi ls --format="json"
+govpp vppapi ls --format="yaml"
 
-# Print as a Go template
-govpp vppapi --format='{{ printf "%+v" . }}'
+# Print using a Go template
+govpp vppapi ls --format='{{ printf "%+v" . }}'
 ```
 
 You can use the `--show-contents`, `--show-messages`, `--show-raw`, and `--show-rpc` 
 flags to show specific parts of the VPP API file(s).
 
 ```sh
-# Print VPP API file contents
-govpp vppapi --show-contents
+# List VPP API contents
+govpp vppapi ls --show-contents
 
-# Print VPP API messages
-govpp vppapi --show-message
+# List VPP API messages
+govpp vppapi ls --show-message
 
-# Print VPP API services
-govpp vppapi --show-rpc
+# List RPC services
+govpp vppapi ls --show-rpc
 
-# Print raw VPP API file
-govpp vppapi --show-raw
+# Print raw VPP API files
+govpp vppapi ls --show-raw
 ```
 
 You can also use the `--include-fields` and `--include-imported` flags to include 
 message fields and imported types, respectively.
 
 For more information on the available flags and options, use the `-h` or `--help` flag.
 
-### Lint VPP API files
+### Run linter for VPP API definitions
 
 The `lint` command allows you to run linter checks for your VPP API files. This can help you catch issues early and ensure that your code follows best practices.
 
 Here's an example usage of the `lint` command:
 
 shell
 ```sh
-govpp lint --input="https://github.com/FDio/vpp.git"
+govpp vppapi lint https://github.com/FDio/vpp.git
 ```
 
 This command runs the linter checks on the `master` branch of official VPP repository and outputs any issues found.
@@ -151,7 +156,7 @@ The `diff` command allows you to compare two VPP API schemas and lists the diffe
 Here's an example usage of the `diff` command:
 
 ```sh
-govpp diff ./vppapi2210 --against ./vppapi2302
+govpp vppapi diff "./vppapi2210" --against "./vppapi2302"
 ```
 
 This command compares the VPP API schema from `vppapi2210` directory against the VPP API schema in `vppapi2302` and lists the differences between them. The output shows related information details for each difference.