Release version v0.15.1 (#2381)

**What this PR does / why we need it**:

**Which issue(s) this PR fixes**:

Fixes #

**Does this PR introduce a user-facing change?**:
<!--
If no, just write "NONE" in the release-note block below.
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```release-note
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This PR was merged by Kapetanios.

docs/content/en/blog/releases/v0.15.1.md

@@ -0,0 +1,19 @@
+---
+title: "Release v0.15.1"
+linkTitle: "Release v0.15.1"
+date: 2021-08-20
+description: >
+  Release v0.15.1
+---
+
+## Changelog since v0.15.0
+
+### Notable Changes
+* Move application count badges to Insights page ([#2377](https://github.com/pipe-cd/pipe/pull/2377))
+* Enable insights tab on header ([#2373](https://github.com/pipe-cd/pipe/pull/2373))
+
+### Internal Changes
+* Disable call insights get data on insight page ([#2379](https://github.com/pipe-cd/pipe/pull/2379))
+* Add make web-test command ([#2378](https://github.com/pipe-cd/pipe/pull/2378))
+* Update manifests to allow specifying cloudrun credentials ([#2375](https://github.com/pipe-cd/pipe/pull/2375))
+* Divide Eventwatcher examples into multiple files ([#2374](https://github.com/pipe-cd/pipe/pull/2374))

release/RELEASE

@@ -1 +1 @@
-version: v0.15.0
+version: v0.15.1