doc: update & move cli usage to docs

docs/VDD_CLI_USAGE.md

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+# Command Line Interface
+
+This is detailed help for CLI mode of the ParsecVDisplay app. The CLI executable
+(`vdd`) can be installed via setup installer and can be invoked via command line
+environment.
+
+> Check out the [Releases page](https://github.com/nomi-san/parsec-vdd/releases)
+> to get the setup installer (from v1.0) which has filename ends with
+> `-setup.exe`.
+
+## Usage
+
+Run the command below to check if `vdd` is installed.
+
+```sh
+vdd -h
+```
+
+If success, you will get the help:
+
+```sh
+vdd command [args...]
+    -a|add           - Add a virtual display
+    -r|remove        - Remove the last added virtual display
+            X        - Remove the virtual display at index X (number)
+            all      - Remove all the added virtual displays
+    -l|list          - Show all the added virtual displays and specs
+    -s|set  X WxH    - Set resolution for a virtual display
+                        where X is index number, WxH is size, e.g 1920x1080
+            X @R     - Set only the refresh rate R, e.g @60, @120 (hz)
+                        on Powershell, you should replace '@' with 'r'
+            X WxH@R  - Set full display mode as above, e.g 1920x1080@144
+    -v|version       - Query driver version and status
+    -h|help          - Show this help
+```
+
+### Adding virtual display
+
+Use command `-a` or `add` to add a virtual display.
+
+```sh
+vdd -a
+```
+
+The exit code is the index of added display, you can reuse this index to remove
+the display. Less than 0 means error occurred.
+
+### Removing virtual display
+
+Use command `-r` or `remove` to remove the last added.
+
+```sh
+vdd -r
+```
+
+Remove the added virtual display at index `0`.
+
+```sh
+vdd -r 0
+```
+
+To remove all the added, replace the index with `all` or `*`.
+
+```
+vdd -r all
+```
+
+### Listing added displays
+
+List all added virtual displays.
+
+```sh
+vdd -l
+```
+
+The exit code is the number of added virtual displays.
+
+Example of output:
+
+```
+Index: 0
+  - Device: \\.\DISPLAY37
+  - Number: 2
+  - Name: PSCCDD0
+  - Mode: 1600 x 900 @ 60 Hz
+  - Orientation: Landscape (0°)
+```
+
+### Setting display mode
+
+A resolution is the display dimension (width x height) in pixels. A display mode
+extends it plus a refresh rate such as 1920 x 1080 @ 60 Hz.
+
+Set resolution for a virtual display at index 1.
+
+```sh
+vdd set 1 1920x1080
+```
+
+With full display mode, plus 120 Hz.
+
+```sh
+vdd set 1 1920x1080 @120
+```
+
+With only refresh rate.
+
+```sh
+vdd set 1 @144
+```
+
+On Powershell terminal, you should replace the symbol `@` with letter `r`.
+
+```powershell
+vdd set 1 1920x1080 r120
+```
+
+The command will fail and exit with non-zero if the display mode is invalid.
+
+### Querying version
+
+Query the driver status and version.
+
+```sh
+vdd -v
+```
+
+Example output:
+
+```
+Parsec Virtual Display Adapter
+- Status: OK
+- Version: 0.45
+```
+
+Here is the list of possible status and its code:
+
+```js
+0   OK                 - Ready to use
+1   INACCESSIBLE       - Inaccessible
+2   UNKNOWN            - Unknown status
+3   UNKNOWN_PROBLEM    - Unknown problem
+4   DISABLED           - Device is disabled
+5   DRIVER_ERROR       - Device encountered error
+6   RESTART_REQUIRED   - Must restart PC to use (could ignore but would have issue)
+7   DISABLED_SERVICE   - Service is disabled
+8   NOT_INSTALLED      - Driver is not installed
+```
+
+The status code is also the exit code of this command.