feat(PAM service configuration) (#62)

* docs(typo): fix typo in Contributing.md

* add optional PAM service name

* feat(PAM service name): Add ENV variable configuration for the PAM service name

* feat(PAM service name): Implement suggested changes + update README instructions

* docs(remove segment)

docs/CONTRIBUTING.md

@@ -2,9 +2,10 @@
 
 Contributions are welcome! Here's how you can help:
 
-* [Contributing code](#code)
-* [Reporting issues](#issues)
-* [Other](#other)
+- [Contributing](#contributing)
+  - [Code](#code)
+  - [Issues](#issues)
+  - [Other](#other)
 
 ## Code
 
@@ -18,7 +19,7 @@ For small fixes or incremental improvements simply fork the repo and follow the
    * Check your code works as expected.
    * Run the code formatter: `clang-format -i $(git ls-files "*.c" "*.h")`
    * Run the code linter: `clang-tidy -p . $(git ls-files "*.c" "*.h")`. Some checks are pretty pedantic, feel free to ignore or debate some of the rules.
-   * If you prefer, you can run `make pre-commit` to run several code style checks like the avobe along a few extra stuff.
+   * If you prefer, you can run `make pre-commit` to run several code style checks like the above along a few extra stuff.
 
 3. Commit your changes to a new branch (not `master`, one change per branch) and push it:
    * Commit messages should: