✏ Update first-steps.md, clarify distinction between parameter and …

…argument (fastapi#176)

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

docs/tutorial/first-steps.md

@@ -401,14 +401,14 @@ are called "Python function parameters" or "Python function arguments".
 
     It's quite technical... and somewhat pedantic.
 
-    One refers to the variable name in a function *declaration*. Like:
+    *Parameter* refers to the variable name in a function *declaration*. Like:
 
     ```
     def bring_person(name: str, lastname: str = ""):
         pass
     ```
 
-    The other refers to the value passed when *calling* a function. Like:
+    *Argument* refers to the value passed when *calling* a function. Like:
 
     ```
     person = bring_person("Camila", lastname="Gutiérrez")