Restructure folders (#411)

Cargo.toml

@@ -1,57 +1,57 @@
 [workspace]
 members = [
-   "async_data_factory",
-   "async_db",
-   "async_ex1",
-   "async_ex2",
-   "async-graphql-demo",
-   "async_pg",
-   "awc_https",
-   "basics",
-   "casbin",
-   "cookie-auth",
-   "cookie-session",
-   "diesel",
-   "docker_sample",
-   "error_handling",
-   "form",
-   "hello-world",
-   "http-proxy",
-   "json",
-   "json_decode_error",
-   "json_error",
-   "jsonrpc",
-   "juniper",
-   "juniper-advanced",
-   "middleware",
-   "multipart",
-   "multipart-s3",
-   "multipart-async-std",
-   "openssl",
-   "protobuf",
-   "r2d2",
-   "redis",
-   "redis-session",
-   "run-in-thread",
-   "rustls",
-   "rustls-client-cert",
-   "shutdown-server",
-   "server-sent-events",
-   "simple-auth-server",
-   "state",
-   "static_index",
-   "template_askama",
-   "template_handlebars",
-   "template_tera",
-   "template_tinytemplate",
-   "template_yarte",
-   "todo",
-   "udp-echo",
-   "unix-socket",
-   "web-cors/backend",
-   "websocket",
-   "websocket-autobahn",
-   "websocket-chat",
-   "websocket-chat-broker",
-   "websocket-tcp-chat"
+   "basics/basics",
+   "basics/docker_sample",
+   "basics/error_handling",
+   "basics/hello-world",
+   "basics/http-proxy",
+   "basics/json-validation",
+   "basics/middleware",
+   "basics/nested-routing",
+   "basics/run-in-thread",
+   "basics/shutdown-server",
+   "basics/state",
+   "basics/static_index",
+   "basics/todo",
+   "database_interactions/basic",
+   "database_interactions/diesel",
+   "database_interactions/pg",
+   "database_interactions/r2d2",
+   "database_interactions/redis",
+   "database_interactions/simple-auth-server",
+   "forms/form",
+   "forms/multipart",
+   "forms/multipart-async-std",
+   "forms/multipart-s3",
+   "graphql/graphql-demo",
+   "graphql/juniper",
+   "graphql/juniper-advanced",
+   "json/json",
+   "json/json_decode_error",
+   "json/json_error",
+   "json/jsonrpc",
+   "other/data_factory",
+   "other/protobuf",
+   "other/server-sent-events",
+   "other/udp-echo",
+   "other/unix-socket",
+   "security/awc_https",
+   "security/casbin",
+   "security/openssl",
+   "security/rustls",
+   "security/rustls-client-cert",
+   "security/web-cors/backend",
+   "session/cookie-auth",
+   "session/cookie-session",
+   "session/redis-session",
+   "template_engines/askama",
+   "template_engines/handlebars",
+   "template_engines/tera",
+   "template_engines/tinytemplate",
+   "template_engines/yarte",
+   "websockets/autobahn",
+   "websockets/chat",
+   "websockets/chat-broker",
+   "websockets/tcp-chat",
+   "websockets/websocket",
 ]