Fix README sql and links

- Fix SQL syntax for create index concurrently
- Use https links where appropriate

Signed-off-by: Nicolas Payart <npayart@gmail.com>

Author: koleo

README.md

@@ -1,6 +1,6 @@
 # sql-migrate
 
-> SQL Schema migration tool for [Go](http://golang.org/). Based on [gorp](https://github.com/go-gorp/gorp) and [goose](https://bitbucket.org/liamstask/goose).
+> SQL Schema migration tool for [Go](https://golang.org/). Based on [gorp](https://github.com/go-gorp/gorp) and [goose](https://bitbucket.org/liamstask/goose).
 
 [![Build Status](https://travis-ci.org/rubenv/sql-migrate.svg?branch=master)](https://travis-ci.org/rubenv/sql-migrate) [![GoDoc](https://godoc.org/github.com/rubenv/sql-migrate?status.svg)](https://godoc.org/github.com/rubenv/sql-migrate)
 
@@ -15,7 +15,7 @@ Using [modl](https://github.com/jmoiron/modl)? Check out [modl-migrate](https://
 * Atomic migrations
 * Up/down migrations to allow rollback
 * Supports multiple database types in one project
-* Works great with other libraries such as [sqlx](http://jmoiron.github.io/sqlx/)
+* Works great with other libraries such as [sqlx](https://jmoiron.github.io/sqlx/)
 
 ## Installation
 
@@ -298,7 +298,7 @@ Normally each migration is run within a transaction in order to guarantee that i
 
 ```sql
 -- +migrate Up notransaction
-CREATE UNIQUE INDEX people_unique_id_idx CONCURRENTLY ON people (id);
+CREATE UNIQUE INDEX CONCURRENTLY people_unique_id_idx ON people (id);
 
 -- +migrate Down
 DROP INDEX people_unique_id_idx;
@@ -383,7 +383,7 @@ type MigrationSource interface {
 
 The resulting slice of migrations will be executed in the given order, so it should usually be sorted by the `Id` field.
 
-## Usage with [sqlx](http://jmoiron.github.io/sqlx/)
+## Usage with [sqlx](https://jmoiron.github.io/sqlx/)
 
 This library is compatible with sqlx. When calling migrate just dereference the DB from your `*sqlx.DB`: