docs: add code samples for str accessor methdos (#594)

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Fixes internal issue 333397327 🦕

Author: shobsi

bigframes/operations/strings.py

@@ -53,7 +53,25 @@ def lower(self) -> series.Series:
         return self._apply_unary_op(ops.lower_op)
 
     def reverse(self) -> series.Series:
-        """Reverse strings in the Series."""
+        """Reverse strings in the Series.
+
+        **Examples:**
+
+            >>> import bigframes.pandas as bpd
+            >>> bpd.options.display.progress_bar = None
+
+            >>> s = bpd.Series(["apple", "banana", "", bpd.NA])
+            >>> s.str.reverse()
+            0     elppa
+            1    ananab
+            2
+            3      <NA>
+            dtype: string
+
+        Returns:
+            bigframes.series.Series: A Series of booleans indicating whether the given
+                pattern matches the start of each string element.
+        """
         # reverse method is in ibis, not pandas.
         return self._apply_unary_op(ops.reverse_op)
 

scripts/get_documentation_coverage.py

@@ -97,6 +97,10 @@ def get_coverage_summary(
             if name.startswith("_") and not name.startswith("__"):
                 continue
 
+            # ignore constructor
+            if name == "__init__":
+                continue
+
             def predicate(impl):
                 return (
                     # This includes class methods like `from_dict`, `from_records`