add FlashDB and TDengine

README.md

@@ -277,6 +277,10 @@ Databases and data stores with C APIs.
   transactional NoSQL engine. [``BSD-2-Clause``][BSD-2-Clause]
 * [WhiteDB][512] - Lightweight database library, operating entirely in main
   memory. [``GPL-3.0-or-later``][GPL-3.0-or-later]
+* [FlashDB][703] - An ultra-lightweight database that supports key-value and 
+  time series data. [``Apache-2.0``][Apache-2.0]
+* [TDengine][704] - High-performance, cloud native time-series database. 
+  [``AGPL-3.0-only``][AGPL-3.0-only]
 
 ## Data Structures ##
 
@@ -1837,3 +1841,6 @@ support for C.
 [700]: https://viewsourcecode.org/snaptoken/kilo/
 [701]: https://wiki.gnome.org/Projects/GLib
 [702]: https://duckdb.org/
+[703]: https://github.com/armink/FlashDB
+[704]: https://github.com/taosdata/TDengine
+