Fix typographical errors in the documentation.

docs/howtos/add_weights.md

@@ -2,7 +2,7 @@
 # Adding Weights Files
 
 Our [first model](../tutorials/write_first_model.md) did not need any weights files.
-We just created weights and bias at runtime.
+We just created weights and biases at runtime.
 
 But real-world models typically need weights files, and maybe some other
 supporting files. 

docs/howtos/howto_torch2zml.md

@@ -258,7 +258,7 @@ pub fn asyncMain() !void {
 
 During this phase, you have three kinds of errors that can appear:
 
-* Zig compilation errors: we've all have been there, learning a new language
+* Zig compilation errors: we've all been there, learning a new language
   can be tough. Normally, the compiler should help you figure out what's wrong.
   You can also check [ZML concepts](../learn/concepts.md) that explains types used
   by ZML.

docs/tutorials/write_first_model.md

@@ -8,7 +8,7 @@
 - add some Bazel to integrate our code with ZML
 - no weights files or anything external is required for this example
 
-The reason we're doing our excercise in the `examples` folder is because it's
+The reason we're doing our exercise in the `examples` folder is because it's
 especially prepared for new ZML projects. It contains everything needed for ZML
 development. From `bazel` configs to `vscode` settings, and `neovim` LSP
 support. The `examples` folder serves as a cookiecutter ZML project example,