[documentation] hyperledger#1991: Add readme to Kura inspector

Signed-off-by: Ekaterina Mekhnetsova <mekkatya@gmail.com>

tools/kura_inspector/README.md

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+# Kura Inspector
+
+Kura Inspector is a CLI tool to inspect blocks in disk storage.
+
+With Kura Inspector you can inspect the disk storage regardless of the operating status of Iroha and print out block contents in a human-readabe format.
+
+## Examples
+
+- Print the contents of the latest block:
+
+  ```bash
+  kura_inspector print
+  ```
+
+- Print all blocks with a height between 100 and 104:
+
+  ```bash
+  kura_inspector -f 100 print -n 5
+  ```
+
+- Print errors for all blocks with a height between 100 and 104:
+
+  ```bash
+  kura_inspector -f 100 print -n 5 >/dev/null
+  ```
+
+## Usage
+
+Run Kura Inspector:
+
+```bash
+kura_inspector [OPTIONS] <SUBCOMMAND>
+```
+
+### Options
+
+|     Option     |                      Description                      |    Default value     |       Type       |
+| -------------- | ----------------------------------------------------- | -------------------- | ---------------- |
+| `-f`, `--from` | The starting block height of the range for inspection | Current block height | Positive integer |
+
+### Subcommands
+
+|      Command      |                     Description                     |
+| ----------------- | --------------------------------------------------- |
+| [`print`](#print) | Print the contents of a specified number of blocks  |
+| `help`            | Print the help message for the tool or a subcommand |
+
+### Errors
+
+An error in Kura Inspector occurs if one the following happens:
+
+- `kura_inspector` fails to configure `kura::BlockStore`
+- `kura_inspector` [fails](#print-errors) to run the `print` subcommand
+
+## `print`
+
+The `print` command reads data from the `block_store` and prints the results to the specified `output`.
+
+|      Option      |                                      Description                                      | Default value |       Type       |
+| ---------------- | ------------------------------------------------------------------------------------- | ------------- | ---------------- |
+| `-n`, `--length` | The number of blocks to print. The excess is truncated.                               | 1             | Positive integer |
+| `-o`, `--output` | Where to write the results of the inspection: valid data and [errors](#print-errors). | `/dev/stdout` | file             |
+
+### `print` errors
+
+An error in `print` occurs if one the following happens:
+- `kura_inspector` fails to read `block_store`
+- `kura_inspector` fails to print the `output`
+- `kura_inspector` tries to print the latest block and there is none