add cdx-toolkit (#135)

Co-authored-by: Greg Lindahl <greg@commomncrawl.org>
Co-authored-by: Andy Jackson <Andrew.Jackson@bl.uk>

README.md

@@ -129,6 +129,7 @@ This list of tools and software is intended to briefly describe some of the most
 
 * [ArchiveTools](https://github.com/recrm/ArchiveTools) - Collection of tools to extract and interact with WARC files (Python).
 <!--lint ignore double-link-->
+* [cdx-toolkit](https://pypi.org/project/cdx-toolkit/) - Library and CLI to consult cdx indexes and create WARC extractions of subsets. Abstracts away Common Crawl's unusual crawl structure. *(Stable)*
 * [Go Get Crawl](https://github.com/karust/gogetcrawl) - Extract web archive data using [Wayback Machine](https://web.archive.org/) and [Common Crawl](https://commoncrawl.org/). *(Stable)*
 * [gowarcserver](https://github.com/nlnwa/gowarcserver) - [BadgerDB](https://github.com/dgraph-io/badger)-based capture index (CDX) and WARC record server, used to index and serve WARC files (Go).
 * [har2warc](https://github.com/webrecorder/har2warc) - Convert HTTP Archive (HAR) -> Web Archive (WARC) format (Python).
@@ -161,7 +162,7 @@ This list of tools and software is intended to briefly describe some of the most
 * [Sparkling](https://github.com/internetarchive/Sparkling) - Internet Archive's Sparkling Data Processing Library. *(Stable)*
 * [Unwarcit](https://github.com/emmadickson/unwarcit) - Command line interface to unzip WARC and WACZ files (Python).
 * [Warcat](https://github.com/chfoo/warcat) - Tool and library for handling Web ARChive (WARC) files (Python). *(Stable)*
-* [warcio](https://github.com/webrecorder/warcio) - Streaming WARC/ARC library for fast web archive IO (Python).
+* [warcio](https://github.com/webrecorder/warcio) - Streaming WARC/ARC library for fast web archive IO (Python). *(Stable)*
 * [warctools](https://github.com/internetarchive/warctools) - Library to work with ARC and WARC files (Python).
 * [webarchive](https://github.com/richardlehane/webarchive) - Golang readers for ARC and WARC webarchive formats (Golang).
 
@@ -172,6 +173,7 @@ This list of tools and software is intended to briefly describe some of the most
 * [Archives Unleashed Notebooks](https://github.com/archivesunleashed/notebooks) - Notebooks for working with web archives with the Archives Unleashed Toolkit, and derivatives generated by the Archives Unleashed Toolkit. *(Stable)*
 * [Archives Unleashed Toolkit](https://github.com/archivesunleashed/aut) - Archives Unleashed Toolkit (AUT) is an open-source platform for analyzing web archives with Apache Spark. *(Stable)*
 * [Tweet Archvies Unleashed Toolkit](https://github.com/archivesunleashed/twut) - An open-source toolkit for analyzing line-oriented JSON Twitter archives with Apache Spark. *(In Development)*
+* [Web Data Commons](http://webdatacommons.org/) - Structured data extracted from Common Crawl. *(Stable)*
 
 ### Quality Assurance
 
@@ -212,6 +214,7 @@ This list of tools and software is intended to briefly describe some of the most
 
 ### Mailing Lists
 
+* [Common Crawl](https://groups.google.com/g/common-crawl)
 * [IIPC](http://netpreserve.org/about-us/iipc-mailing-list/)
 * [OpenWayback](https://groups.google.com/g/openwayback-dev)
 * [WASAPI](https://groups.google.com/g/wasapi-community)