add docker dev files , needed to start dev in docker environment.

Dockerfile

@@ -0,0 +1,10 @@
+FROM gogs/gogs:0.12
+
+# In docker "custom" dir is /data/gogs/ and there is no need to create named "custom" dir
+# there, /data/gogs/ works by default as custom.
+WORKDIR /data/gogs/
+RUN mkdir -p templates/inject && mkdir -p public/css/themes \
+&&  mkdir -p public/img 
+
+# ADD ./themes /data/gogs/public/css/themes
+# ADD ./img /data/gogs/public/img/

docker-compose.yml

@@ -0,0 +1,21 @@
+version: "3"
+
+services:
+  gogs:
+    build:
+      context: .
+      dockerfile: ./Dockerfile
+    container_name: gogs
+    restart: unless-stopped 
+    volumes:
+      - "gogs_data:/data"
+      - "./themes:/data/gogs/public/css/themes"
+      - "./img:/data/gogs/public/img"
+      - "./header.tmpl:/data/gogs/templates/inject/head.tmpl"
+    ports:
+      - "10022:22"
+      - "3000:3000"
+
+volumes:
+  gogs_data:
+ 

header.tmpl

@@ -0,0 +1 @@
+<link rel="stylesheet" href="/css/themes/dark_theme.css">

install.sh

@@ -1,3 +1,5 @@
+#!/bin/bash
+
 mkdir -p ../custom/templates/inject/
 mkdir -p ../custom/public/css/
 rm ../custom/templates/inject/head.tmpl