zstd: add page (#2646)

pages/common/zstd.md

@@ -0,0 +1,23 @@
+# zstd
+
+> Compress or decompress files with Zstandard compression.
+
+- Compress a file into a new file with the .zst suffix:
+
+`zstd {{file}}`
+
+- Decompress a file:
+
+`zstd -d {{file}}.zst`
+
+- Decompress to stdout:
+
+`zstd -dc {{file}}.zst`
+
+- Compress a file, while specifing the compression level. 0 = Worst, 19 = Best (Default level is 3):
+
+`zstd -{{level}} {{file}}`
+
+- Use more memory (both when compressing and decompressing) to achieve a higher compression ratio:
+
+`zstd --ultra -{{level}} {{file}}`