doc hardnested compression options

doc/md/Use_of_Proxmark/3_Commands-and-Features.md

@@ -8,6 +8,7 @@
   - [To get interactive help](#to-get-interactive-help)
   - [New Features in RDV4](#new-features-in-rdv4)
   - [Useful commands](#useful-commands)
+- [Hardnested tables](#hardnested-tables)
 
 
 
@@ -58,3 +59,31 @@ A good starting point is the following [Cheat sheet](/doc/cheatsheet.md)
 Or 
 
 this compilation of links to [Proxmark3 walk throughs](https://github.com/RfidResearchGroup/proxmark3/wiki/More-cheat-sheets)
+
+# Hardnested tables
+^[Top](#top)
+
+Hardnested tables are compressed with LZ4 for a good compromise between space and decompression speed.
+
+If you are under very space constrained environment, you can recompress the tables with BZip2 and delete the LZ4. It will break the git workdir but if space is a concern, you're not deploying the source and `.git` of > 80Mb anyway, do you?
+
+```sh
+cd client/resources/hardnested_tables
+lz4 -dm --rm *lz4
+bzip2 *.bin
+```
+
+If you want top speed, you can decompress the tables in advance. Keep the `.lz4` files, so you can always just `rm *.bin` to save space again.
+
+```sh
+cd client/resources/hardnested_tables
+lz4 -dkm *lz4
+```
+
+| Compression | Size in Mb |   Speed(*)  |
+|-------------|:----------:|:-----------:|
+| LZ4         | 9          | 1           |
+| BZip2       | 2          | 6.5x slower |
+| None        | 704        | 2.5x faster |
+
+(*) rough idea of relative speeds, real numbers depend on your actual system