Docs: Add transformations documentation (#24597)

* Create transformations.md

* Update transformations.md

* Create calculations-list.md

* Update transformations.md

* Update menu.yaml

* Update transformations.md

* Update calculations-list.md

* updated menu

* Delete text.md

Deleted old text panel topic

* Update transformations.md

* added content

* Update transformations.md

* Update whats-new-in-v7-0.md

* Update transformations.md

* Update docs/sources/panels/transformations.md

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

* Update docs/sources/panels/transformations.md

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

* Update docs/sources/panels/transformations.md

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

* Update docs/sources/panels/calculations-list.md

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

* Update docs/sources/panels/transformations.md

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

* Update transformations.md

* fixed broken links

Co-authored-by: Dominik Prokop <dominik.prokop@grafana.com>

docs/sources/panels/visualizations/news-panel.md

@@ -6,7 +6,7 @@ type = "docs"
 name = "news-panel"
 parent = "visualizations"
 weight = 850
-draft = "true"
+draft = "false"
 +++
 
 ## News panel

docs/sources/panels/visualizations/text-panel.md

@@ -7,7 +7,7 @@ aliases = ["/docs/grafana/latest/reference/alertlist/", "/docs/grafana/latest/fe
 name = "text-panel"
 parent = "visualizations"
 weight = 700
-draft = "true"
+draft = "false"
 +++
 
 # Text panel