Update deploy script

* [Changed] move everything inside /build/ directory
* [Changed] use absolute file paths in script
* [Changed] copy docs to both the release number and master dirs
Implement @PhrozenByte 's suggestions.
* [Changed] use `$GITHUB_OAUTH_TOKEN` instead of `$GITHUB_TOKEN`

build/deploy-phpdoc.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Modified from: https://gist.github.com/domenic/ec8b0fc8ab45f39403dd
+
+# Exit with nonzero exit code if anything fails
+set -e
+
+# Clone Pico, then create & checkout gh-pages branch
+git clone -b gh-pages "https://github.com/picocms/Pico.git $TRAVIS_BUILD_DIR/build/Pico"
+
+# Inside this git repo we'll pretend to be a new user
+git config user.name "Travis CI"
+git config user.email "travis-ci@picocms.org"
+
+#copy new files to release number
+cp -a $TRAVIS_BUILD_DIR/build/docs/pico-$TRAVIS_TAG $TRAVIS_BUILD_DIR/build/Pico/phpDoc/pico-$TRAVIS_TAG
+#move old files
+mv -f $TRAVIS_BUILD_DIR/build/Pico/phpDoc/master $TRAVIS_BUILD_DIR/build/Pico/phpDoc/old-stable
+#copy new files to master
+cp -a $TRAVIS_BUILD_DIR/build/docs/pico-$TRAVIS_TAG $TRAVIS_BUILD_DIR/build/Pico/phpDoc/master
+
+# Add the files to our commit
+git add $TRAVIS_BUILD_DIR/build/Pico/phpDoc/*
+
+# Commit the files with our commit message
+git commit -m "Update Documentation for Pico $TRAVIS_TAG"
+
+# Force push from the current repo's master branch to the remote
+# repo's gh-pages branch.We redirect any output to
+# /dev/null to hide any sensitive credential data that might otherwise be exposed.
+git push --force --quiet "https://${GITHUB_OAUTH_TOKEN}@${GH_REF}" master:gh-pages > /dev/null 2>&1