[DOC] Adding a brief documentation for standalone sub-section's Steel book

docs/src/start/standalone.md

@@ -1 +1,113 @@
 # Using Steel on its own
+
+## Preambule
+This document includes some features of ABNF (Augmented Backus Naur form), which is a meta-language used to define
+another language and proves itself always useful in documentations associated with programming languages and softwares.
+To know more about its full specifications, see: [RFC5234](https://www.rfc-editor.org/rfc/rfc5234) and its superseeded
+RFC at [RFC7405](https://www.rfc-editor.org/rfc/rfc7405) (fixing case-sensitivity).
+
+The main considerations are defined as follow:
+  - \<file\> = defines a logical entity between angle brackets, with a concept's name or identifier
+  - \<cmd-1\> / \<cmd-2\> = a *solidus* (as named by the Unicode consortium, more commonly known as "slash") stands for "alternative
+  OR" (also known as XOR, or exlusive OR) and is inserted between two operands, forms, or S-expressions.
+  - [option] = a optional concept is encompassed between square brackets.
+  - ``=` = the equal sign is not a affection per-se but stands for a business rule that is defined by a associated name.
+    That is to say: \<name\> = \<rule\>
+
+Of course, those semantic mechanisms will NOT appear anywhere in your command lines!
+
+## Installing Steel Interpreter
+
+You can use and enjoy all features provided by the Steel Interpreter by installing it and running it on its own.
+
+1. To proceed, let us start by cloning the official Steel project's repository:\
+  `git clone https://github.com/mattwparas/steel` [my_custom_target_name]
+
+*Nota bene*: A second optional argument allows you to customize the target directory (*i.e.* steel_lang)
+
+2. Rendez-vous into the newly created directory:\
+`cd steel / \<custom_dir_name\>`
+
+3. You have 3 slightly different manners to make use of the Steel interpreter:\
+  - You can rely on the Rust package manager (*i.e.* Cargo):\
+    `cargo run`\
+    It will install all the required crates to prepare your environment, which are merely dependencies in Rust 
+    ecosystem's vocabulary.
+
+    Then run `cargo run -- \<steel_file.scm\>` every time you need to execute the said Steel file.\
+
+    That is all for this sub-section if you decide to take this route!
+
+  - Alternatively, you can install the Steel interpreter and simply run it as it is a more straightforward way to 
+  proceed. To achieve this, here is the canonical way to install a package with Cargo:\
+  `cargo install --path .`
+
+*Nota bene*: forget not the trailing dot (*i.e.* `.`) as it represents your current working directory.
+
+  - There is a second manner to install Steel interpreter with Cargo. The only difference is that it reads your 
+  `cargo.lock` file if it exists.\
+  As a side note, having added the `--locked` flag to the previous `cargo install --path .` command would have 
+  produced the exact same result than the following one.
+
+  Simply run:\
+  `cargo build --release`
+
+  The release flag will take a bit longer to build all the file objects due to optimization passes but will act faster
+  when executing subsequent runs.
+
+
+## Updating interactive shell environment
+
+  4. Add the portable binary executable path name to your `PATH` environment variable.
+
+    - For those who adopt Bash or Zsh as their daily driver, simply feed the new path like the following:\
+  `export PATH=~/\<your/path/to/steel/directory\>/target/release:$PATH`
+
+  Then run the subsequent command to regenerate your environment variable:\
+  `source ~/.bashrc`
+
+    - With respect to `Fish` shell users, simply proceed this way:\
+  `fish_add_path \<your/path/to/steel/directory\>/target/release`
+
+  Now reload your interactive shell with the newly added environment variable like so:\
+  `source ~/.config/fish/config.fish`
+
+  - And for those who make use of `elvish` as their beloved shell, add the following into your `rc.elv` file:\
+  ```
+  set paths = [
+    ~/\<your/path/to/steel/directory\>/target/release`
+  $@paths]
+  ```
+
+  Finally, just type:\
+  `exec elvish`
+
+  You can optionally check if your $paths environment variable has been properly fed with the new path name:\
+  `pprint $paths`
+
+
+## Running a Steel file
+
+  5. Finally, compile and execute your Steel files from your terminal like so:\
+  `steel \<steel_file.scm\>`
+
+
+### Installing built-in modules
+
+  7. Define `STEEL_HOME` and add it as a new environment variable. It will serve a your default location to install 
+  subsequent packages to preserve a sane installation tree.
+  You can try a hidden directory to avoid remove it by accident:
+  `export PATH=${PWD}/.steel:$PATH`
+
+  Of course, you adopt the method to update your `PATH` variable according to your actual shell. See sub-section n°4 of
+  the current document for more details on how to proceed.
+  Like before, forget not to regenerate your interactive shell to activate the new path name without having to start a
+  new user session.
+
+  8. Navigate through the installer sub-directory and run the built-in modules' installation:
+  `cd cogs`\
+  `cargo --run install.scm`
+
+  9. Finally, install the code coverage tool test, which will be of great use in the case you intend to contribute to
+  Steel development:
+  `cargo install cargo-tapaulin`