Driver/R: Improve page based on latest standards, and copy-editing

Author: amotl

docs/connect/r.md

@@ -16,27 +16,28 @@ RPostgres is actively maintained and often preferred.
 :::{rubric} Synopsis
 :::
 
+`example.r`
 ```r
-# RPostgres: C++ Interface to PostgreSQL
+# Connect to CrateDB from R, using the "RPostgres: C++ Interface to PostgreSQL".
 # https://cran.r-project.org/web/packages/RPostgres/
 
-# Optionally install the PostgreSQL library on demand.
+# Install the Postgres library on demand.
 if (!requireNamespace("RPostgres", quietly = TRUE)) {
     install.packages("RPostgres", repos="https://cran.r-project.org")
 }
 
-# Load the DBI and PostgreSQL libraries.
+# Load the DBI and Postgres libraries.
 library(DBI)
 library(RPostgres)
 
-# Open a database connection, where `dbname` is the name of the CrateDB schema.
+# Connect to database.
 conn <- dbConnect(RPostgres::Postgres(),
                   host = "localhost",
                   port = 5432,
                   sslmode = "disable",
                   user = "crate",
                   password = "crate",
-                  dbname = "testdrive",
+                  dbname = "doc"
                   )
 on.exit(DBI::dbDisconnect(conn), add = TRUE)
 
@@ -45,13 +46,32 @@ res <- dbGetQuery(conn, "SELECT * FROM sys.summits ORDER BY height DESC LIMIT 10
 print(res)
 ```
 
-:::{note}
-**⚠️ Security note:** The example uses hardcoded credentials and disables SSL
-for simplicity. In production, use environment variables or secrets management
-(e.g., `.Renviron`, keyvault) and enable TLS verification
-(`sslmode="verify-full"` or `"require"`).
+Start CrateDB using Docker or Podman, then invoke the example program.
+```shell
+docker run --rm --publish=5432:5432 crate -Cdiscovery.type=single-node
+```
+```shell
+Rscript example.r
+```
+
+
+:::{rubric} CrateDB Cloud
 :::
 
+For connecting to CrateDB Cloud, use `sslmode = "require"`, and
+replace username, password, and hostname with values matching
+your environment.
+```r
+conn <- dbConnect(RPostgres::Postgres(),
+                  host = "testcluster.cratedb.net",
+                  port = 5432,
+                  sslmode = "require",
+                  user = "admin",
+                  password = "password",
+                  dbname = "doc"
+                  )
+```
+
 ## Example
 
 :::{card}