Add more detail to the README.

README

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 -*- mode: org -*-
 
-This Guile library provides useful patterns and functionality to use
+* Guile Knots
-Guile Fibers.
+
+Guile Knots is a library providing higher-level patterns and building
+blocks for programming with [[https://codeberg.org/guile/fibers][Guile Fibers]].
+
+This includes:
+
+- Parallel map/for-each with configurable concurrency limits
+- Resource and thread pools
+- Fiber-aware promises for lazy and eager parallel evaluation
+- Timeouts for fibers and I/O ports
+- A HTTP web server
+- Non-blocking socket utilities