Misc improvements to README (#111)

Author: Luni-4

README.md

@@ -4,7 +4,8 @@
 
 This project is a Rust crate (library) to analyse source code. This software is based on [Tree Sitter](https://github.com/tree-sitter/tree-sitter).
 
-It supports several languages:
+## Supported Languages
+
 * C++
 * C#
 * CSS
@@ -17,17 +18,67 @@ It supports several languages:
 * Rust
 * Typescript
 
-## How to build it
+## Supported Metrics
+
+- CC: it calculates the code complexity examining the
+control flow of a program.
+- SLOC: it counts the number of lines in a source file.
+- LLOC: it counts the number of logical lines (instructions) contained in a source file.
+- HALSTEAD: it is a suite that provides a series of information, such as the effort required to maintain the analyzed code, the size in bits to store the program, the difficulty to understand the code, an estimate of the number of bugs present in the codebase, and an estimate of the time needed to implement the software.
+- NEXITS: it counts the number of possible exit points from a method/function.
+- NARGS: it counts the number of arguments of a function/method.
+
+## How to get metrics
+
+You can get metrics in your shell in this way
+
+```
+rust-code-analysis --metrics --paths /your/path/to/a/file
+```
+
+or as a `json` file
+
+```
+rust-code-analysis --metrics --output your/path/to/the/output/directory --paths /your/path/to/a/file
+```
+
+or you can run it as a `HTTP` service and use its `REST API`
+
+
+```
+rust-code-analysis --serve --port 9090
+```
 
-```console
-# Fetch the tree-sitter dependencies
-git submodule init
-git submodule update --recursive
 
-# Now build with cargo
+## How to build the software
+
+Clone the repository and its submodules through HTTPS
+
+```
+git clone --recurse-submodules -j8 https://github.com/mozilla/rust-code-analysis.git
+```
+
+or through SSH
+
+```
+git clone --recurse-submodules -j8 git@github.com:mozilla/rust-code-analysis.git
+```
+
+Build and run `rust-code-analysis`
+
+```console
+# Build with cargo
 cargo build
 
-# It should be available through cargo now
+# Run through cargo
 cargo run -- -h
 cargo run -- --serve --port 8000
 ```
+
+## How to run tests
+
+After the build step, run the following command in order to verify if all tests pass
+
+```
+cargo test --verbose
+```