Update tableau.md (#4380)

Adding note about versions we just tested and referencing the cumulative
metric w/ grain issue to remind people in Tableau docs as well

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website/docs/docs/use-dbt-semantic-layer/tableau.md

@@ -16,7 +16,7 @@ This integration provides a live connection to the dbt Semantic Layer through Ta
 
 ## Prerequisites
 
-1. You must have [Tableau Desktop](https://www.tableau.com/en-gb/products/desktop) installed
+1. You must have [Tableau Desktop](https://www.tableau.com/en-gb/products/desktop) installed with version 2021.1 or greater
 2. Log in to Tableau Desktop using either your license or the login details you use for Tableau Server or Tableau Online.
 3. You need your dbt Cloud host, [Environment ID](/docs/use-dbt-semantic-layer/setup-sl#set-up-dbt-semantic-layer) and [service token](/docs/dbt-cloud-apis/service-tokens) to log in. This account should be set up with the dbt Semantic Layer.
 4. You must have a dbt Cloud Team or Enterprise [account](https://www.getdbt.com/pricing) and multi-tenant [deployment](/docs/cloud/about-cloud/regions-ip-addresses). (Single-Tenant coming soon)
@@ -53,6 +53,7 @@ Visit the [Tableau documentation](https://help.tableau.com/current/pro/desktop/e
    - Since this is treated as a table, dbt Semantic Layer can't dynamically change what is available. This means we display _all_ available metrics and dimensions even if a particular metric and dimension combination isn't available. 
 
 - Certain Table calculations like "Totals" and "Percent Of" may not be accurate when using metrics aggregated in a non-additive way (such as count distinct)
+- In any of our Semantic Layer interfaces (not only Tableau), you must include a [time dimension](/docs/build/cumulative#limitations) when working with any cumulative metric that has a time window or granularity.
 
 ## Unsupported functionality
 
@@ -67,3 +68,4 @@ The following Tableau features aren't supported at this time, however, the dbt S
 - All functions in Analysis --> Create Calculated Field
 - Filtering on a Date Part time dimension for a Cumulative metric type
 - Changing your date dimension to use "Week Number"
+