Makefile: update target (#449)

Add sqlc-dev as a dependency of the "regen" target to lower the
possibility that someone is running regenerate with an out of date
sqlc binary.

Also update the docs to refer to the Make target instead of the
script.

Author: kevinburke1

Makefile

@@ -7,5 +7,5 @@ test:
 sqlc-dev:
 	go build -o ~/bin/sqlc-dev --tags=exp ./cmd/sqlc/
 
-regen:
+regen: sqlc-dev
 	./scripts/regenerate.sh

README.md

@@ -350,7 +350,7 @@ scopes the override behavior to just a single package:
 
 ```yaml
 version: "1"
-packages: 
+packages:
   - overrides: [...]
 ```
 
@@ -464,7 +464,7 @@ go build -o ~/go/bin/sqlc-dev ./cmd/sqlc
 ### Running Tests
 
 To run the tests, include the `exp` tag. Without this tag, a few tests will
-fail. 
+fail.
 
 ```
 go test --tags=exp ./...
@@ -494,9 +494,12 @@ If you need to update a large number of expected test output in the
 `internal/endtoend/testdata` directory, run the `regenerate.sh` script.
 
 ```
-./scripts/regenerate.sh
+make regen
 ```
 
+Note that this uses the `sqlc-dev` binary, not `sqlc` so make sure you have an
+up to date `sqlc-dev` binary.
+
 ## Acknowledgements
 
 sqlc was inspired by [PugSQL](https://pugsql.org/) and