tighten Tutorial intro + Contributing opener

Two micro-edits to remove conversational filler from doc openers
without changing meaning:

  TUTORIAL.md  drop 'We'll go from … in a single sitting' phrasing,
               read more directly as 'From git clone to Pocket talks
               to your AI, in one sitting.'

  CONTRIBUTING strip the 'Thanks for considering a contribution'
               opener — go straight to what the project is and what
               keeping it that way means.

Author: Zawwarsami16

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 # Contributing to zhub
 
-Thanks for considering a contribution. zhub is intentionally small: each file does one thing, the test bar is high, and the public surface stays neutral. Keeping it that way is the contribution.
+zhub is intentionally small: each file does one thing, the test bar is high, the public surface stays neutral. Keeping it that way is the contribution.
 
 ## Setup
 

docs/TUTORIAL.md

@@ -1,6 +1,6 @@
 # zhub in 10 minutes — hands-on
 
-Goal: by the end of this, you have an OpenAI-compatible AI endpoint reachable from your phone. We'll go from `git clone` to "Pocket talks to your AI" in a single sitting.
+Goal: by the end, you have an OpenAI-compatible AI endpoint reachable from your phone. From `git clone` to "Pocket talks to your AI", in one sitting.
 
 ## Minute 0–2: install