Add readme

README.md

+# Do not kill me library
+
+An Android library helping to keep a foreground service with wake-locks running. No other use-cases considered.
+
+## Include in your project
+
+    implementation 'org.briarproject:dont-kill-me-lib:[version]'
+
+where `[version]` is the latest version.
+
+## Publishing
+
+To publish latest release in staging repo on maven central:
+
+    ./gradlew publish
+
+To do the actual release from staging repo to maven central:
+
+    ./gradlew closeAndReleaseRepository
+
+Alternatively, visit https://oss.sonatype.org/#stagingRepositories and release there.