docs: Remove unnecessary comment marks from the Makefile help section (#21749)

**Previous screenshot:**
<img width="758" alt="image"
src="https://github.com/langchain-ai/langchain/assets/1683919/7b90626e-35ab-4486-b41d-b664e69eec0b">

**Current:**
<img width="744" alt="image"
src="https://github.com/langchain-ai/langchain/assets/1683919/cdb69512-dc6c-4b7f-a466-4be92d94c076">

Makefile

@@ -3,7 +3,7 @@
 ## help: Show this help info.
 help: Makefile
 	@printf "\n\033[1mUsage: make <TARGETS> ...\033[0m\n\n\033[1mTargets:\033[0m\n\n"
-	@sed -n 's/^##//p' $< | awk -F':' '{printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}' | sort | sed -e 's/^/ /'
+	@sed -n 's/^## //p' $< | awk -F':' '{printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}' | sort | sed -e 's/^/  /'
 
 ## all: Default target, shows help.
 all: help