ADD: below.

README.md

@@ -19,11 +19,11 @@ If you want to contribute through a pull request, make sure to add new entries t
 
 # Summary
 
-To date, **322** apps/tools covered, divided in **32** categories.
+To date, **323** apps/tools covered, divided in **32** categories.
 
 # Index
 
-[Backup](#backup) (9) | [Chat and instant messaging](#chat) (7) | [Conversion](#conversion) (4) | [Data management](#data-management) (8) | [Data transfer](#transfer) (21) | [Editors](#editors) (14) | [Email](#email) (8) | [File and file system handling](#file-handling) (23) | [File manager](#file-manager) (8) | [File systems](#file-system) (3) | [Font management](#font) (2) | [Funny tools](#funny) (9) | [Games](#games) (16) | [Graphics](#graphics) (7) | [Networking](#networking) (7) | [Office tools](#office) (10) | [Organizers and calendars](#organizers) (21) | [Productivity](#productivity) (10) | [Programming](#programming) (3) | [Security and encryption](#security) (14) | [Shells](#shells) (3) | [Sound and music](#music) (14) | [System monitoring](#monitor) (18) | [System tools](#system) (7) | [Terminals](#terminal) (6) | [Text processing](#text-processing) (13) | [Text search](#text-search) (5) | [Utilities](#utility) (21) | [Versioning](#versioning) (8) | [Viewers](#viewers) (12) | [Web browser](#browser) (6) | [Web development](#webdev) (5)
+[Backup](#backup) (9) | [Chat and instant messaging](#chat) (7) | [Conversion](#conversion) (4) | [Data management](#data-management) (8) | [Data transfer](#transfer) (21) | [Editors](#editors) (14) | [Email](#email) (8) | [File and file system handling](#file-handling) (23) | [File manager](#file-manager) (8) | [File systems](#file-system) (3) | [Font management](#font) (2) | [Funny tools](#funny) (9) | [Games](#games) (16) | [Graphics](#graphics) (7) | [Networking](#networking) (7) | [Office tools](#office) (10) | [Organizers and calendars](#organizers) (21) | [Productivity](#productivity) (10) | [Programming](#programming) (3) | [Security and encryption](#security) (14) | [Shells](#shells) (3) | [Sound and music](#music) (14) | [System monitoring](#monitor) (19) | [System tools](#system) (7) | [Terminals](#terminal) (6) | [Text processing](#text-processing) (13) | [Text search](#text-search) (5) | [Utilities](#utility) (21) | [Versioning](#versioning) (8) | [Viewers](#viewers) (12) | [Web browser](#browser) (6) | [Web development](#webdev) (5)
 
 Some links to [related resources](#resources).
 
@@ -316,6 +316,7 @@ Some links to [related resources](#resources).
 
 ## <a name="monitor"></a>System monitoring
 
+* [below](https://github.com/facebookincubator/below) - A time traveling resource monitor for modern Linux systems
 * [bpytop](https://github.com/aristocratos/bpytop) - Linux/OSX/FreeBSD resource monitor with a nice interface.
 * [cv](https://github.com/Xfennec/progress) - (Coreutils Progress Viewer) "looks for coreutils basic commands (`cp`, `mv`, `dd`, `tar`, `gzip/gunzip`, `cat`, etc.) currently running on your system and displays the percentage of copied data. It can also show estimated time and throughput".
 * [dmidecode](https://www.nongnu.org/dmidecode/) - System information utility.

data/apps.csv

@@ -321,3 +321,4 @@ music,castero,https://github.com/xgi/castero,A TUI podcast client for the termin
 security,GnuPG,https://gnupg.org/,GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
 chat,tiny,https://github.com/osa1/tiny,tiny is an IRC client written in Rust.
 productivity,Standard Unix Notes,https://github.com/Standard-Unix-Notes/unix-notes,GPG Encrypted Notes/Notebook manager for BSD/Linux.
+monitor,below,https://github.com/facebookincubator/below,A time traveling resource monitor for modern Linux systems