Add *philosophy* and *under the hood* sections

README.md

@@ -1,13 +1,26 @@
 # `protoc-gen-gotemplate`
 :open_file_folder: protocol generator + golang text/template (protobuf)
 
-Generic protocol buffer generator backed by Golang's [text/template](https://golang.org/pkg/text/template).
+A generic **code**/script/data generator based on [Protobuf](https://developers.google.com/protocol-buffers/).
 
 ---
 
 This is a generator plugin for the Google Protocol Buffers compiler (`protoc`).
 
-The plugin can generate files based on a template directory using the [Golang's `text/template`](https://golang.org/pkg/text/template/) engine.
+The plugin parses **protobuf** files, generates an **ast**, and walks a local **templates directory** to generate files using the [Golang's `text/template` engine](https://golang.org/pkg/text/template/).
+
+## Philosophy
+
+* protobuf-first
+* no built-in template, only user defined templates
+* kiss, *keep it stupid simple*
+
+## Under the hood
+
+1. the *user* `protobuf` files are parsed by [`protoc`](https://github.com/google/protobuf/releases)
+2. the `ast` is generated by [`protoc-gen-go` helpers](https://github.com/golang/protobuf/tree/master/protoc-gen-go)
+3. the `ast` is given to [Golang's `text/template` engine](https://golang.org/pkg/text/template/) for each *user* template files
+4. the *funcmap* enriching the template engine is based on [Masterminds/sprig](https://github.com/Masterminds/sprig), and contains type-manipulation, iteration and language-specific helpers
 
 ## Usage
 
@@ -52,6 +65,10 @@ Non-exhaustive list of new helpers:
 
 See the project helpers for the complete list.
 
+## Hacks
+
+
+
 ## Install
 
 * Install the **Go** compiler and tools from https://golang.org/doc/install