ect: add page (#2951)

pages/common/ect.md

@@ -0,0 +1,16 @@
+# ect
+
+> Efficient Compression Tool (or ECT) is a C++ file optimizer. It supports PNG, JPEG, GZIP and ZIP files.
+> Homepage: <https://github.com/fhanau/Efficient-Compression-Tool>.
+
+- Compress a file:
+
+`ect {{filename.png}}`
+
+- Compress a file with the highest compression level and multithreading:
+
+`ect -9 --mt-deflate {{filename.png}}`
+
+- Compress all the files in a directory recursively, keeping the original modification time:
+
+`ect -keep -recurse {{directory}}`