Optimize draw calls for HTML build, update README

example/custom.texture_profiles

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+path_settings {
+  path: "**"
+  profile: "Default"
+}
+profiles {
+  name: "Default"
+  platforms {
+    os: OS_ID_GENERIC
+    formats {
+      format: TEXTURE_FORMAT_RGBA
+      compression_level: BEST
+      compression_type: COMPRESSION_TYPE_DEFAULT
+    }
+    mipmaps: false
+    max_texture_size: 0
+    premultiply_alpha: true
+  }
+}