Add custom markdown template

This template does the following:
- Adds an indication that the the field in a message has the `oneof`
property
- Removes the table of contents (Mkdocs automatically adds one for us
when we use this file in the SDK docs)

Other than that the output should be the same as with the standard
template.

Author: sindrehan

markdown.tmpl

@@ -0,0 +1,49 @@
+# Protocol Documentation
+{{range .Files}}
+{{$file_name := .Name}}
+<a name="{{.Name | anchor}}"></a>
+
+## {{.Name}}
+{{.Description}}
+
+{{range .Messages}}
+<a name="{{.FullName | anchor}}"></a>
+
+### {{.LongName}}
+{{.Description}}
+
+{{ if .HasFields}}
+| Field | Type | Description |
+| ------| ---- | ----------- |
+{{range .Fields -}}
+| {{if .IsOneof -}}<small>{{if eq .OneofDecl (printf "_%s" .Name)}}<strong>optional</strong>{{else}}<strong>oneof</strong> <code>{{.OneofDecl}}</code>{{end}}</small><br>{{end}}{{.Name}} {{/* noline */ -}}
+| [{{if .IsMap}}map{{else}}{{.Label}} {{end}}{{.LongType}}](#{{.FullType | anchor}}) {{/* noline */ -}}
+| {{if (index .Options "deprecated" | default false)}}**deprecated**<br>{{end}}{{if .Description}}{{.Description | replace "\n" "<br>"}}{{end}} {{/* noline */ -}}
+|
+{{end}}{{/* range .Fields */}}
+{{- end}}{{/* if .HasFields */}}
+{{- end}}{{/* range .Messages */}}
+
+{{range .Enums}}
+<a name="{{.FullName | anchor}}"></a>
+
+### {{.LongName}}
+{{.Description}}
+
+| Name | Number | Description |
+| ---- | ------ | ----------- |
+{{range .Values -}}
+  | {{.Name}} | {{.Number}} | {{nobr .Description}} |
+{{end}}
+
+{{end}}
+
+{{- end}}{{/* range .Files */}}
+
+## Scalar Value Types
+
+| .proto Type | Notes | C++ | Java | Python | Go | C# | PHP | Ruby |
+| ----------- | ----- | --- | ---- | ------ | -- | -- | --- | ---- |
+{{range .Scalars -}}
+  | <a name="{{.ProtoType | anchor}}" /> {{.ProtoType}} | {{.Notes}} | {{.CppType}} | {{.JavaType}} | {{.PythonType}} | {{.GoType}} | {{.CSharp}} | {{.PhpType}} | {{.RubyType}} |
+{{end}}

protoc-gen-doc.sh

@@ -4,7 +4,8 @@ echo "Generating Markdown documentation $(pwd)/docs/markdown/protocol.md"
 docker run --rm \
   -v $(pwd)/docs/markdown:/out \
   -v $(pwd)/protobuf_definitions:/protos \
-  pseudomuto/protoc-gen-doc --doc_opt=markdown,protocol.md
+  -v $(pwd)/markdown.tmpl:/markdown.tmpl \
+  pseudomuto/protoc-gen-doc --doc_opt=markdown.tmpl,protocol.md
 
 echo "Generating HTML documentation $(pwd)/docs/html/protocol.html"
 docker run --rm \