Fix: add alt tags and fix headers

Author: lwasser

_pages/learn.md

@@ -18,8 +18,8 @@ overview:
   - excerpt: "pyOpenSci creates resources to help you navigate the Python packaging ecosystem with ease. Our materials are community developed and go through extensive technical and pedagogical review."
 development:
    - image_path: images/pyopensci-learn-community-created.png
-     alt: "alt here "
-     title: "Our Development Process: Community-developed Python Tutorials for Scientists"
+     alt: "An image showing a bunch of hands holding up a sign that says Community Developed. the background is dark purple with a few green decorative items."
+     title: "Our development process: Community-developed Python tutorials for scientists"
      excerpt: "Our tutorials are created through a multi-stage community review process.
 
      * Tutorials are developed by the pyOpenSci team or community members.
@@ -29,7 +29,7 @@ development:
      * Before publication, tutorials then go through several rounds of community review for accuracy, usability and accessibility."
 whats_next:
   - image_path: images/pyopensci-learn-github-collaboration.png
-    alt: "A pencil sketch of a round table with people sitting around it from different backgrounds working on laptops and also writing together."
+    alt: "A graphic with a light yellow background that says essential collaboration skills for scientists - using GitHub. On the right there is a man and a woman sitting at a tall table with laptops working."
     excerpt: "Through the [Better Software for Science Fellowship](https://bssw.io/pages/bssw-fellowship-program) we will be developing lessons focused on teaching core GitHub collaboration skills needed for both contributing to open source software and for working in an open science team environment.
 
 
@@ -55,7 +55,7 @@ toc: false
 <!-- Feature wrapper has a clear both -->
 <div class="feature__wrapper padded" markdown="1">
 
-## Start Learning: Beginner-friendly Python packaging tutorials
+## Start learning: Beginner-friendly Python packaging tutorials
 
 Beginner-friendly Python packaging tutorials that will take you through
 the full process of creating a Python package, following modern best