data-structures: fix ordering

Order alphabetically the list of entries in data-structures section.

README.md

@@ -274,22 +274,22 @@ Databases and data stores with C APIs.
 * [CLIST][371] - Simple and lightweight [dynamic array][25] implementation.
   [``BSD-2-Clause``][BSD-2-Clause]
 * [Collections-C][406] - Library of generic data structures. [``LGPL-3.0-or-later``][LGPL-3.0-or-later]
-* [kdtree][337] - Simple library for working with KD-trees. [``BSD-3-Clause``][BSD-3-Clause]
-* [libavl][156] - Library containing a range of self-balancing binary
-  trees. [``GPL-3.0-or-later``][GPL-3.0-or-later]
 * [ds][541] - Common Data Structures and Algorithms. [``MIT``][MIT]
 * [igraph][544] - A graph processing library.
   [``GPL-2.0-or-later``][GPL-2.0-or-later]
+* [kdtree][337] - Simple library for working with KD-trees. [``BSD-3-Clause``][BSD-3-Clause]
+* [libavl][156] - Library containing a range of self-balancing binary
+  trees. [``GPL-3.0-or-later``][GPL-3.0-or-later]
 * [liblfds][411] - Portable lock-free data structure library. Public domain
   (more exactly, whatever license you want).
-* [M\*LIB][350] - Library for generic, but typesafe C containers. Implemented as
-  header-only. [``BSD-2-Clause``][BSD-2-Clause]
-* [offbrand][498] - Collection of generic, reference-counted data structures.
-  [``MIT``][MIT]
 * [libsrt][305] - Soft and hard real-time data structures.
   [``BSD-3-Clause``][BSD-3-Clause].
 * [list.h][538] - Implementations for singly linked and doubly linked list functions.
   [``GPL-3.0-only``][GPL-3.0-only]
+* [M\*LIB][350] - Library for generic, but typesafe C containers. Implemented as
+  header-only. [``BSD-2-Clause``][BSD-2-Clause]
+* [offbrand][498] - Collection of generic, reference-counted data structures.
+  [``MIT``][MIT]
 * [PackedArray][241] - Random-access array of tightly packed unsigned integers of
   any desired width. Has a SIMD-optimized implementation. [``WTFPL``][WTFPL]
 * [rb3ptr][561] - Red-Black tree. Exposes almost all implementation primitives, so can be used for