docs(developer-guide): update instructions

1. README
2. ADR workflow
3. API guidelines

GH-5

docs/adr/0001-record-architecture-decisions.md

@@ -26,6 +26,8 @@ We need to record the architectural decisions made on this project, since:
 
 We will document every architecture-level decision for `getting-started-inner-source` and its core modules with an [Architecture Decision Record][nygard-article-url]. These are a well structured, relatively lightweight way to capture architectural proposals. They can serve as an artifact for discussion, and remain as an enduring record of the context and motivation of past decisions.
 
+### Architecture decision workflow
+
 The workflow will be:
 
 1. A community member creates an ADR document outlining an approach for a particular question or problem. The ADR has an initial status of "proposed."

docs/developer-guide/README.md

@@ -2,6 +2,23 @@
 
 > <img align="bottom" alt="code" height="50" width="50" src="https://cdnjs.cloudflare.com/ajax/libs/octicons/4.4.0/svg/code.svg"> This guide is for those who want to contribute code to `getting-started-inner-source`. This guide describes how to set up your development environment so that you can build and test `getting-started-inner-source`.
 
+## Table of contents
+
+<!-- toc -->
+
+- [1. Recommended skills](#1-recommended-skills)
+- [2. Development software](#2-development-software)
+- [3. Getting the source code](#3-getting-the-source-code)
+- [4. Installing dependencies](#4-installing-dependencies)
+- [5. Building](#5-building)
+- [6. Running tests](#6-running-tests)
+- [7. Source code style guidelines](#7-source-code-style-guidelines)
+- [8. DevSecOps](#8-devsecops)
+
+<!-- tocstop -->
+
+<!-- tocend -->
+
 ## 1. Recommended skills
 
 In order to work with `getting-started-inner-source` as a developer, we recommend you: