RELEASE.md: update release notes

Update release notes with an extra system requirement, instructions of
how to install NDK in Android Studio as well as instructions of how to
generate an Open Timestamp.

RELEASE.md

@@ -7,6 +7,14 @@ This document describes the steps needed to release a new version of LNC binarie
 1. Android Studio with Android SDK (API level 16 or newer)
 2. Xcode (latest version)
 3. Go v1.19.8 or newer
+4. javac version 1.7 or higher (Included in Java Development Kit 7+)
+
+#### Android Studio SDK tools requirements
+
+Ensure that NDK is installed for the Android Studio SDK tools.
+To install NDK in Android Studio, navigate to Preferences (or Settings) |
+Appearance & Behavior | System Settings | Android SDK. Navigate to the SDK Tools
+tab, mark `NDK (Side by side)` and then click the "Apply" button.
 
 ### Build Release Binaries
 
@@ -35,6 +43,12 @@ When this completes, a `build` dir will be created with four files:
 $ gpg --default-key {PGP_EMAIL} --output manifest-{GITHUB_USERNAME}-vX.Y.Z-alpha.sig --detach-sign manifest-vX.Y.Z-alpha.txt
 ```
 
+#### Create an Open Timestamp for the signed manifest
+
+Go to https://opentimestamps.org. Upload the newly generated
+`manifest-{GITHUB_USERNAME}-vX.Y.Z-alpha.sig` signature file, and download the
+resulting `ots` file.
+
 ### Create a tag and push to Github
 
 Using the `-s` option signs the tag with your PGP key
@@ -52,13 +66,14 @@ On Github create a new release. Select the tag you just pushed, then click the
 Take the rest of the content from a previous release. Be sure to update the
 version number and update the verification examples to use your own PGP key.
 
-In the assets, include these five files:
+In the assets, include these six files:
 
 - lnc-vX.Y.Z-alpha.wasm
 - lnc-vX.Y.Z-alpha-android.zip
 - lnc-vX.Y.Z-alpha-ios.zip
 - manifest-vX.Y.Z-alpha.txt
 - manifest-{GITHUB_USERNAME}-vX.Y.Z-alpha.sig
+- manifest-{GITHUB_USERNAME}-v0.2.5-alpha.sig.ots
 
 ### Deploy the WASM binary to CDN