docs: update README (#63)

README.md

@@ -48,8 +48,9 @@ It's not a complete example of The Clean Architecture itself
 package `app` embeds "Entities" layer), but it does show the most relevant
 part: how to create "API Controller" layer in package `srv/openapi`
 between code auto-generated by go-swagger and "Use Cases" layer in package
-`app`. Also it includes "DB Gateway" layer in package `dal/memory` (provided
-trivial in-memory implementation is "DB" and "Gateway" layers at once).
+`app`. Also it includes "DB Gateway" layer in packages `dal/memory` (provided
+trivial in-memory implementation is "DB" and "Gateway" layers at once) and
+`dal/mysql` (just "Gateway" layer).
 
 ### The hexagonal architecture, or ports and adapters architecture
 
@@ -59,7 +60,7 @@ adapters":
 - "ports" are defined as interfaces in `app/app.go` - they make it
   possible to easily test business-logic in `app` without any external
   dependencies by mocking all these interfaces.
-- "adapters" are implemented in `srv/*` (serve project APIs), `dal`
+- "adapters" are implemented in `srv/*` (serve project APIs), `dal/*`
   (access DB) and `svc/*` (use external services) packages - they can't be
   tested that easy, so they should be as thin and straightforward as
   possible and try hard to do nothing than convert ("adapt") data between
@@ -74,7 +75,7 @@ adapters":
   application(s) subcommands and tests
 - `internal/app` - define interfaces ("ports") and implements business-logic
 - `internal/srv/*` - adapters for served APIs/UI
-- `internal/dal` - adapter for data storage
+- `internal/dal/*` - adapters for data storage
 - `internal/svc/*` - adapters for accessing external services
 - `pkg/*` - helper packages, not related to architecture and
   business-logic (may be later moved to own modules and/or replaced by