Add python readme for Search. (#15873)

Author: tjprescott

specification/search/data-plane/Azure.Search/readme.python.md

@@ -0,0 +1,49 @@
+## Python
+
+These settings apply only when `--python` is specified on the command line.
+Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
+Use `--python-mode=update` if you already have a setup.py and just want to update the code itself.
+
+``` yaml
+license-header: MICROSOFT_MIT_NO_VERSION
+payload-flattening-threshold: 1
+package-name: azure-search-documents
+clear-output-folder: true
+no-namespace-folders: true
+```
+
+### Tag: package-2020-06-searchservice-preview
+
+These settings apply only when `--tag=package-2020-06-searchservice-preview` is specified on the command line.
+
+``` yaml $(tag) == 'package-2020-06-searchservice-preview'
+namespace: azure.search.documents.indexes
+output-folder: $(python-sdks-folder)/search/azure-search-documents/azure/search/documents/indexes/_generated
+```
+
+### Tag: package-2020-06-searchindex-preview
+
+These settings apply only when `--tag=package-2020-06-searchindex-preview` is specified on the command line.
+
+``` yaml $(tag) == 'package-2020-06-searchindex-preview'
+namespace: azure.search.documents
+output-folder: $(python-sdks-folder)/search/azure-search-documents/azure/search/documents/_generated
+```
+
+### Tag: package-2021-04-searchservice-preview
+
+These settings apply only when `--tag=package-2021-04-searchservice-preview` is specified on the command line.
+
+``` yaml $(tag) == 'package-2021-04-searchservice-preview'
+namespace: azure.search.documents.indexes
+output-folder: $(python-sdks-folder)/search/azure-search-documents/azure/search/documents/indexes/_generated
+```
+
+### Tag: package-2021-04-searchindex-preview
+
+These settings apply only when `--tag=package-2021-04-searchindex-preview` is specified on the command line.
+
+``` yaml $(tag) == 'package-2021-04-searchindex-preview'
+namespace: azure.search.documents
+output-folder: $(python-sdks-folder)/search/azure-search-documents/azure/search/documents/_generated
+```