Rename WithCompressionType to WithCompression. (#1116)

Rename the builder method WithCompressionType added in #1013 to
WithCompression to be consistent with the option struct field
named Compression.

Update the godoc for WithCompression with the default compression
algorithm used.

options.go

@@ -488,11 +488,14 @@ func (opt Options) WithKeepL0InMemory(val bool) Options {
 	return opt
 }
 
-// WithCompressionType returns a new Options value with CompressionType set to the given value.
+// WithCompression returns a new Options value with Compression set to the given value.
 //
-// When compression type is set, every block will be compressed using the specified algorithm.
+// When compression is enabled, every block will be compressed using the specified algorithm.
 // This option doesn't affect existing tables. Only the newly created tables will be compressed.
-func (opt Options) WithCompressionType(cType options.CompressionType) Options {
+//
+// The default compression algorithm used is zstd when built with Cgo. Without Cgo, the default is
+// snappy. Compression is enabled by default.
+func (opt Options) WithCompression(cType options.CompressionType) Options {
 	opt.Compression = cType
 	return opt
 }