Document humanoid model changes in changelog section of its README + minor cosmetic improvements.

PiperOrigin-RevId: 595367344
Change-Id: I17483de71c6cbcf6a66e2fad762cc32f8cbee8b5

model/humanoid/README.md

@@ -1,17 +1,35 @@
-Humanoid
+# Humanoid
-========
-
-Degrees of Freedom: 27
-Actuators: 21
 
 This simplified humanoid model, introduced in [1], is designed for bipedal locomotion
 behaviours. While several variants of it exist in the wild, this version is based on the model
 in the DeepMind Control Suite [2], which has fairly realistic actuator gains.
 
+* Degrees of Freedom: 27
+* Actuators: 21
+
+<p float="left">
+  <img src="humanoid.png" width="400">
+</p>
+
+## Changelog
+
+* 02-01-2024: Add more keyframes.
+* 27-11-2023: Move humanoid geoms to group 1.
+* 05-04-2023: Fix typo in texture size.
+* 20-09-2022: Use default class for left_upper_arm geom.
+* 17-09-2022: Increase offscreen render buffer resolution of the humanoid to 2560x1440.
+* 12-09-2022:
+  * Increased maximum hip flexion.
+  * Symmetrised shoulder and ankle joints.
+  * Added hamstring tendons which couple the hip and knee at large flexion values.
+  * Moved duplicated values into defaults.
+  * Added two keyframes.
+  * Improved lighting.
+  * Changed naming convention.
+
+## References
+
 [1] [Synthesis and Stabilization of Complex Behaviors through Online Trajectory Optimization]
      (https://doi.org/10.1109/IROS.2012.6386025).
 
 [2] [DeepMind Control Suite](https://arxiv.org/abs/1801.00690).
-
-
-![humanoid](humanoid.png)