fix Test-CredentialStoreItem return (#66)

#### 📖 Summary

- `Test-CredentialStoreItem` now returns `$false` and not a terminating error if store doesn't exists.
- Updates platyPS generated docs

#### 📑 Test Plan

> 💡 Select your test plan for the code changes.

- [x] Tested via Drone.io pipeline
- [ ] Custom test
- [ ] No test plan

##### Details / Justification

<!-- Add your test details or justification for missing tests here. -->

#### 📚 Additional Notes

- fixes #50

Co-authored-by: OCram85 <marco.blessing@googlemail.com>
Reviewed-on: #66

docs/Readme.md

@@ -0,0 +1,64 @@
+---
+Module Name: PSCredentialStore
+Module Guid: 6800e192-9df8-4e30-b253-eb2c799bbe84
+Download Help Link: {{ Update Download Link }}
+Help Version: {{ Update Help Version }}
+Locale: en-US
+---
+
+# PSCredentialStore Module
+## Description
+See global Readme file for usage instructions.
+
+## PSCredentialStore Cmdlets
+### [Connect-To](Connect-To.md)
+Connects to the given host using the stored CredentialStoreItem.
+
+### [Disconnect-From](Disconnect-From.md)
+Terminates a session established with Connect-To using a CredentialStoreItem.
+
+### [Get-CredentialStore](Get-CredentialStore.md)
+Reads the complete content of the credential store and returns it as a new object.
+
+### [Get-CredentialStoreItem](Get-CredentialStoreItem.md)
+Returns the Credential from a given remote host item.
+
+### [Get-CSCertificate](Get-CSCertificate.md)
+Returns the current used valid PfX certificate.
+
+### [Import-CSCertificate](Import-CSCertificate.md)
+Imports a linked certificate to the valid store location.
+
+### [New-CredentialStore](New-CredentialStore.md)
+Creates a new credential store File
+
+### [New-CredentialStoreItem](New-CredentialStoreItem.md)
+Adds a credential store item containing host, user and password to the given store.
+
+### [New-CSCertAttribute](New-CSCertAttribute.md)
+Creates required data for a certificate signing request.
+
+### [New-CSCertificate](New-CSCertificate.md)
+Creates a new PFX certificate for the CredentialStore encryption.
+
+### [Remove-CredentialStoreItem](Remove-CredentialStoreItem.md)
+Remove the given credentials from the credential store.
+
+### [Set-CredentialStoreItem](Set-CredentialStoreItem.md)
+Changes the credentials for the given remote host in the store.
+
+### [Test-CredentialStore](Test-CredentialStore.md)
+Returns the credential store state.
+
+### [Test-CredentialStoreItem](Test-CredentialStoreItem.md)
+Checks if the given RemoteHost identifier combination exists in the credential store.
+
+### [Test-CSCertificate](Test-CSCertificate.md)
+Tests if the linked certificate is store ein the specified cert stores.
+
+### [Test-CSConnection](Test-CSConnection.md)
+Returns the connection state of a given type to the remote host.
+
+### [Use-CSCertificate](Use-CSCertificate.md)
+Links an existing PFX Certificate to a CredentialStore.
+