show current version changelog section in docs & link externally to full

This is going to fail and output nothing for -pre and -rc tags for now
until #3046 is addressed. We can't yet grab those but still have final
releases sort after them.

ios/docs/install_docs.sh

@@ -17,7 +17,7 @@ README=/tmp/mbgl/GL-README.md
 cat ./pod-README.md > ${README}
 echo >> ${README}
 echo -n "#" >> ${README}
-cat ../../CHANGELOG.md >> ${README}
+cat ../../CHANGELOG.md | sed -n "/^## iOS ${DOCS_VERSION}/,/^##/p" | sed '$d' >> ${README}
 # Copy headers to a temporary location where we can substitute macros that appledoc doesn't understand.
 cp -r ../../include/mbgl/ios /tmp/mbgl
 perl \

ios/docs/pod-README.md

@@ -5,3 +5,5 @@ An open source OpenGL-based vector map solution for iOS with full styling capabi
 For more information, check out [our online overview](https://www.mapbox.com/ios-sdk/). 
 
 [![](https://raw.githubusercontent.com/mapbox/mapbox-gl-native/master/ios/screenshot.png)]()
+
+See the [full changelog](https://github.com/mapbox/mapbox-gl-native/blob/master/CHANGELOG.md) online.

scripts/ios/package.sh

@@ -128,7 +128,7 @@ README=/tmp/mbgl/README.md
 cat ios/docs/pod-README.md > ${README}
 echo >> ${README}
 echo -n "#" >> ${README}
-cat CHANGELOG.md >> ${README}
+cat CHANGELOG.md | sed -n "/^## iOS ${DOCS_VERSION}/,/^##/p" | sed '$d' >> ${README}
 # Copy headers to a temporary location where we can substitute macros that appledoc doesn't understand.
 cp -r "${OUTPUT}/static/Headers" /tmp/mbgl
 perl \