build.go: introduce a friendlier way to build Ollama (#3548)

This commit introduces a more friendly way to build Ollama dependencies
and the binary without abusing `go generate` and removing the
unnecessary extra steps it brings with it.

This script also provides nicer feedback to the user about what is
happening during the build process.

At the end, it prints a helpful message to the user about what to do
next (e.g. run the new local Ollama).

README.md

@@ -201,16 +201,10 @@ Install `cmake` and `go`:
 brew install cmake go
 ```
 
-Then generate dependencies:
-
-```
-go generate ./...
-```
-
 Then build the binary:
 
 ```
-go build .
+go run build.go
 ```
 
 More detailed instructions can be found in the [developer guide](https://github.com/ollama/ollama/blob/main/docs/development.md)