docs(android): add 7.1.2 release notes, drop the inactive WebView note from 7.1.1

[krassx]

Two changes, both about not documenting WebView work that is not live yet.

Adds release notes for Android SDK 7.1.2, which is out. The release is native-crash-reporting focused, so the notes lead with the window that was previously uncovered — a crash in the first moments of the first launch after an install or update, before the out-of-process handler is ready — plus crashes that kill the app before it can report anything, reports assembled before capture was running, and a damaged handler that looked healthy while producing an empty report.

It also documents the addSecureView() / removeSecureView() signature change (Fragment → Object), with a :::note that it needs a rebuild rather than an AAR swap. Source is unaffected: passing a fragment still works.

Removes the WebView bridge bullet from 7.1.1. That change is inert until the matching Bugsee JavaScript package ships, so the entry described behavior no one can observe and pointed readers at a "matching Bugsee JavaScript SDK" that is not out. The summary line above it promised "dependencies and WebView privacy", so that half is gone too — leaving it would have advertised a change the entry no longer makes.

Neither 7.1.1 nor 7.1.2 now refers to the WebView work. It can be documented in whichever release makes it observable.

Style follows the existing 7.1.1 entry (intro line, flat bullets, admonition for the caveat) rather than the sectioned format used further down the page.

Checked: npx cspell clean on the file, and npm run build succeeds (the HTML-minifier diagnostics in its output are pre-existing, on an unrelated Xamarin page).