docs: adding skeleton README.md files for all vlib modules (#13034)

vlib/compress/README.md

@@ -0,0 +1,4 @@
+## Description:
+
+`compress` is a namespace for (multiple) compression algorithms supported by V.
+At the moment, only `compress.zlib` is implemented.

vlib/compress/zlib/README.md

@@ -0,0 +1,16 @@
+## Description:
+
+`compress.zlib` implements zlib compression and decompression of binary data.
+
+## Examples:
+
+```v
+import compress.zlib
+
+fn main() {
+	uncompressed := 'Hello world!'
+	compressed := zlib.compress(uncompressed.bytes()) ?
+	decompressed := zlib.decompress(compressed) ?
+	assert decompressed == uncompressed.bytes()
+}
+```