docs: fix the resource list in the README intro

"datasets" names no API surface — nothing in hotdata/ mentions
datasets; the resource is instant databases (DatabasesApi). And
"workspace context" misnames DatabaseContextApi, whose methods
(get/list/upsert/delete_database_context) attach context to a
database, not the workspace. Also adopts the "instant database"
wording the changelog standardizes for hand-written prose.

Author: eddietejeda

README.md

@@ -1,6 +1,6 @@
 # hotdata
 
-Official Python client for the [Hotdata](https://www.hotdata.dev) HTTP API: workspaces, connections, datasets, SQL queries, results, uploads, indexes, jobs, embedding providers, and workspace context.
+Official Python client for the [Hotdata](https://www.hotdata.dev) HTTP API: workspaces, connections, instant databases, SQL queries, results, uploads, indexes, jobs, embedding providers, and database context.
 
 ## Requirements