fix: correct pipe precedence docs — |> binds tighter than +

R's |> has higher precedence than +, so parentheses ARE required
around the ggplot chain before piping to civilytics_logo():

  (ggplot(df, aes(x, y)) + geom_point() + theme_civilytics()) |>
    civilytics_logo()

Updated docs, examples, and pipe test accordingly.

tests/testthat/test_theme.R

@@ -190,8 +190,11 @@ test_that("civilytics_logo returns a grob", {
 })
 
 test_that("civilytics_logo works with pipe operator", {
-  p <- ggplot(mpg, aes(displ, hwy)) + geom_point() + theme_civilytics()
-  result <- suppressWarnings(p |> civilytics_logo())
+  # |> has higher precedence than +, so parens are required
+  result <- suppressWarnings(
+    (ggplot(mpg, aes(displ, hwy)) + geom_point() + theme_civilytics()) |>
+      civilytics_logo()
+  )
   expect_s3_class(result, "grob")
 })