Replace YAML with HTML in F-Droid fastlane summary (#873)

When using the fastlane structure, F-Droid requires summaries to be marked up with HTML instead of YAML: https://gitlab.com/fdroid/fdroiddata/-/merge_requests/6844#note_365752950.

fastlane/metadata/android/en-US/full_description.txt

@@ -1,13 +1,13 @@
-Simple password manager that is compatible with [https://www.passwordstore.org/
-pass]: Passwords are stored in simple text files which are encrypted with
-OpenPGP.
+Simple password manager that is compatible with <a href="https://www.passwordstore.org/">pass</a>: Passwords are stored in simple text files which are encrypted with OpenPGP.
 
-Requires [[org.sufficientlysecure.keychain]] to encrypt and decrypt passwords.
+Requires <a href="https://f-droid.org/en/packages/org.sufficientlysecure.keychain/">OpenKeychain</a> to encrypt and decrypt passwords.
 
-'''Features:'''
+<strong>Features:</strong>
 
-* Clone an existing pass repository or start a new one
-* Create and organize password files
-* Sync with a remote Git repository
-* Decrypt and copy passwords
-* Automatically fill and save credentials in apps and supported browsers
+<ul>
+<li>Clone an existing pass repository or start a new one</li>
+<li>Create and organize password files</li>
+<li>Sync with a remote Git repository</li>
+<li>Decrypt and copy passwords</li>
+<li>Automatically fill and save credentials in apps and supported browsers</li>
+</ul>