Added documentation for the BitBucket Pipelines integration

Author: davidkeaveny

docs/input/docs/reference/build-servers/bitbucket-pipelines.md

@@ -0,0 +1,78 @@
+---
+Order: 35
+Title: BitBucket Pipelines
+Description: Details on the Atlassian BitBucket Pipelines support in GitVersion
+RedirectFrom: docs/build-server-support/build-server/bitbucket-pipelines
+---
+
+## Basic Usage
+
+To use GitVersion with Atlassian BitBucket Pipelines, you will need to install and run the GitVersion CLI tool
+in your build step.
+
+## Executing GitVersion
+
+### Using the GitVersion CLI tool
+
+An example pipeline is shown below:
+
+```yml
+image: mcr.microsoft.com/dotnet/sdk:6.0
+
+clone:
+  depth: full
+
+pipelines:
+  default:
+    - step:
+      name: Version and build
+      script:
+        - export PATH="$PATH:/root/.dotnet/tools"
+        - dotnet tool install --global GitVersion.Tool --version 5.*
+        - dotnet-gitversion /buildserver
+        - source gitversion.env
+        - echo Building with semver $GITVERSION_FULLSEMVER
+        - dotnet build
+```
+
+:::{.alert .alert-danger}
+**Important**
+
+You must set the `clone:depth` setting as shown above; without it, BitBucket Pipelines will perform a shallow clone, which will
+cause GitVersion will display an error message.
+:::
+
+When the action `dotnet-gitversion /buildserver` is executed, it will detect that it is running in BitBucket Pipelines by the presence of
+the `BITBUCKET_WORKSPACE` environment variable, which is set by the BitBucket Pipelines engine. It will generate a text file named `gitversion.env`
+which contains all the output of the GitVersion tool, exported as individual environment variables prefixed with `GITVERSION_`.
+These environment variables can then be imported back into the build step using the `source gitversion.env` action.
+
+If you want to share the text file across multiple build steps, then you will need to save it as an artifact. A more complex example pipeline
+is shown below:
+
+```yml
+image: mcr.microsoft.com/dotnet/sdk:6.0
+
+clone:
+  depth: full
+
+pipelines:
+  default:
+    - step:
+      name: Version
+      script:
+        - export PATH="$PATH:/root/.dotnet/tools"
+        - dotnet tool install --global GitVersion.Tool --version 5.*
+        - dotnet-gitversion /buildserver
+      artifacts:
+        - gitversion.env
+    - step:
+      name: Build
+      script:
+        - source gitversion.env
+        - echo Building with semver $GITVERSION_FULLSEMVER
+        - dotnet build
+```
+
+[Variables and Secrets](https://support.atlassian.com/bitbucket-cloud/docs/variables-and-secrets/)
+[Clone Options](https://bitbucket.org/blog/support-for-more-clone-options-at-the-step-level)