Add zstd compression support to documentation

- Update documentation to include zstd algorithm description
- Add zstd examples in configuration samples
- Update release notes and README to mention zstd support

Author: JakeChampion

doc/admin-guide/plugins/compress.en.rst

@@ -186,9 +186,19 @@ supported-algorithms
 
 Provides the compression algorithms that are supported, a comma separate list
 of values. This will allow |TS| to selectively support ``gzip``, ``deflate``,
-and brotli (``br``) compression. The default is ``gzip``. Multiple algorithms can
-be selected using ',' delimiter, for instance, ``supported-algorithms
-deflate,gzip,br``. Note that this list must **not** contain any white-spaces!
+brotli (``br``), and zstd (``zstd``) compression. The default is ``gzip``.
+Multiple algorithms can be selected using ',' delimiter, for instance,
+``supported-algorithms deflate,gzip,br,zstd``. Note that this list must **not**
+contain any white-spaces!
+
+============== =================================================================
+Algorithm      Description
+============== =================================================================
+gzip           Standard gzip compression (default, widely supported)
+deflate        Deflate compression (RFC 1951)
+br             Brotli compression (modern, efficient)
+zstd           Zstandard compression (fast, high compression ratio)
+============== =================================================================
 
 Note that if :ts:cv:`proxy.config.http.normalize_ae` is ``1``, only gzip will
 be considered, and if it is ``2``, only br or gzip will be considered.
@@ -233,6 +243,23 @@ might create a configuration with the following options::
    flush true
    supported-algorithms br,gzip
 
+   # Supports zstd compression for high efficiency
+   [zstd.compress.com]
+   enabled true
+   compressible-content-type text/*
+   compressible-content-type application/json
+   compressible-content-type application/javascript
+   flush true
+   supported-algorithms zstd,gzip
+
+   # Supports all compression algorithms
+   [all.compress.com]
+   enabled true
+   compressible-content-type text/*
+   compressible-content-type application/json
+   flush true
+   supported-algorithms zstd,br,gzip,deflate
+
    # This origin does it all
    [bar.example.com]
    enabled false

doc/release-notes/whats-new.en.rst

@@ -81,6 +81,7 @@ Plugins
 * xdebug - ``--enable`` option to selectively enable features has been added
 * system_stats - Stats about memory have been added
 * slice plugin - This plugin was promoted to stable.
+* compress plugin - Added support for Zstandard (zstd) compression algorithm.
 
 JSON-RPC
 ^^^^^^^^

plugins/compress/README

@@ -1,7 +1,7 @@
 What this plugin does:
 =====================
 
-This plugin compresses responses, via gzip or brotli, whichever is applicable
+This plugin compresses responses, via gzip, deflate, brotli, or zstd (Zstandard), whichever is applicable
 it can compress origin responses as well as cached responses
 
 installation:

plugins/compress/sample.compress.config

@@ -56,7 +56,7 @@ allow !*/bla*
 
 minimum-content-length 1024
 #supported algorithms
-supported-algorithms br,gzip
+supported-algorithms br,gzip,zstd
 
 #override the global configuration for a host.
 #www.foo.nl does NOT inherit anything