Update custom-aliases: usage methods, File formatting, and version nu…

…mbers (#4119)

## What are you changing in this pull request and why?
* Updated first version for Dispatch to 1.0. I'm using it in 1.4 so it
had to be introduced before what was stated. The `dispatch` doc page
says 1.0. I also updated the link to have the in-page reference it
seemed to want. I re-titled the section header so it would stand out in
the right navigation and be more descriptive.
* I added the File macro around two files that were missing it.
* I added an example of configuring an alias in YAML instead of Jinja.

## Checklist
- [x] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
and [About
versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
so my content adheres to these guidelines.
- [x] Add a checklist item for anything that needs to happen before this
PR is merged, such as "needs technical review" or "change base branch."

website/docs/docs/build/custom-aliases.md

@@ -34,6 +34,19 @@ select * from ...
 
 </File>
 
+Or in a `schema.yml` file.
+
+<File name='models/google_analytics/schema.yml'>
+
+```yaml
+- models:
+    - name: ga_sessions
+      config:
+        alias: sessions
+```
+
+</File>
+
 When referencing the `ga_sessions` model above from a different model, use the `ref()` function with the model's _filename_ as usual. For example:
 
 <File name='models/combined_sessions.sql'>
@@ -114,34 +127,35 @@ The default implementation of `generate_alias_name` simply uses the supplied `al
 
 </VersionBlock>
 
-<VersionBlock firstVersion="1.6">
 
-### Managing different behaviors across packages
+### Dispatch macro - SQL alias management for databases and dbt packages
 
-See docs on macro `dispatch`: ["Managing different global overrides across packages"](/reference/dbt-jinja-functions/dispatch)
+See docs on macro `dispatch`: ["Managing different global overrides across packages"](/reference/dbt-jinja-functions/dispatch#managing-different-global-overrides-across-packages)
 
-</VersionBlock>
 
 ### Caveats
 
 #### Ambiguous database identifiers
 
 Using aliases, it's possible to accidentally create models with ambiguous identifiers. Given the following two models, dbt would attempt to create two <Term id="view">views</Term> with _exactly_ the same names in the database (ie. `sessions`):
 
-```sql
--- models/snowplow_sessions.sql
+<File name='models/snowplow_sessions.sql'>
 
+```sql
 {{ config(alias='sessions') }}
 
 select * from ...
 ```
+</File>
 
-```sql
--- models/sessions.sql
+<File name='models/sessions.sql'>
 
+```sql
 select * from ...
 ```
 
+</File>
+
 Whichever one of these models runs second would "win", and generally, the output of dbt would not be what you would expect. To avoid this failure mode, dbt will check if your model names and aliases are ambiguous in nature. If they are, you will be presented with an error message like this:
 
 ```