_content/doc: module naming best practices

This adds new content with best practices for the module path. It also
revises existing content to use the best practice.

This change includes:

* A new "Naming a module" section in "Managing dependencies" describing
  naming best practices and reserved terms for module paths.
* Changing module path prefix from "example.com/*" to "example/*"
  where the content seems aimed specifically at new users. This is
  designed to reduce confusion for those who wonder if a domain name
  is required in the local, simple context.
* Links to the "Naming a module" section so that new users can follow up
  from the simple case to learn about best practices.

Change-Id: I07eac1f805ce506a486d3c0e7b54539554e3c30b
Reviewed-on: https://go-review.googlesource.com/c/website/+/344469
Trust: Steve Traut <straut@google.com>
Trust: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/_content/doc/tutorial/database-access.md b/_content/doc/tutorial/database-access.md
index 16a3d7c1..361021f2 100644
--- a/_content/doc/tutorial/database-access.md
+++ b/_content/doc/tutorial/database-access.md
@@ -78,14 +78,18 @@ To begin, create a folder for the code you'll write.
     Run the `go mod init` command, giving it your new code's module path.
 
     ```
-    $ go mod init example.com/data-access
-    go: creating new go.mod: module example.com/data-access
+    $ go mod init example/data-access
+    go: creating new go.mod: module example/data-access
     ```
 
     This command creates a go.mod file in which dependencies you add will be
     listed for tracking. For more, be sure to see
     [Managing dependencies](/doc/modules/managing-dependencies).
 
+    **Note:** In actual development, you'd specify a module path that's
+    more specific to your own needs. For more, see
+    [Managing dependencies](/doc/modules/managing-dependencies#naming_module).
+
 Next, you'll create a database.
 
 ## Set up a database {#set_up_database}