Update Merge Blitz.ps1 so not hardcoded to directory path

This change updates the script such that it'll run on other
peoples' machines, even when they don't have a folder path
that is specific to Brent's developer machine.

Documentation/Development/Merge Blitz.ps1

@@ -1,24 +1,28 @@
 #Set your file path
-$FilePath = "/Users/brentozar/LocalOnly/Github/SQL-Server-First-Responder-Kit"
-$SqlVersionsPath = "$FilePath/SqlServerVersions.sql"
-$BlitzFirstPath = "$FilePath/sp_BlitzFirst.sql"
+$RepoRootPath = $PSScriptRoot
+$RepoRootPath = Join-Path -Path $RepoRootPath -ChildPath ".."
+$RepoRootPath = Join-Path -Path $RepoRootPath -ChildPath ".."
+$RepoRootPath = Resolve-Path -Path $RepoRootPath
+
+$SqlVersionsPath = "$RepoRootPath/SqlServerVersions.sql"
+$BlitzFirstPath = "$RepoRootPath/sp_BlitzFirst.sql"
 
 #Azure - skip sp_Blitz, sp_BlitzBackups, sp_DatabaseRestore, sp_ineachdb
-Get-ChildItem -Path "$FilePath" -Filter "sp_Blitz*.sql" |
+Get-ChildItem -Path "$RepoRootPath" -Filter "sp_Blitz*.sql" |
 Where-Object { $_.FullName -notlike "*sp_Blitz.sql*" -and $_.FullName -notlike "*sp_BlitzBackups*" -and $_.FullName -notlike "*sp_DatabaseRestore*"} |
-ForEach-Object { Get-Content $_.FullName } | 
-Set-Content -Path "$FilePath/Install-Azure.sql" -Force
+ForEach-Object { Get-Content $_.FullName } |
+Set-Content -Path "$RepoRootPath/Install-Azure.sql" -Force
 if ( test-path "$BlitzFirstPath")
-	{ Add-Content -Path "$FilePath/Install-All-Scripts.sql" -Value (Get-Content -Path "$BlitzFirstPath")}
-	
+	{ Add-Content -Path "$RepoRootPath/Install-All-Scripts.sql" -Value (Get-Content -Path "$BlitzFirstPath")}
+
 
 #All Scripts
-Get-ChildItem -Path "$FilePath" -Filter "sp_*.sql" |
+Get-ChildItem -Path "$RepoRootPath" -Filter "sp_*.sql" |
 Where-Object { $_.FullName -notlike "*sp_BlitzInMemoryOLTP*" -and $_.FullName -notlike "*sp_BlitzFirst*"} |
-ForEach-Object { Get-Content $_.FullName } | 
-Set-Content -Path "$FilePath/Install-All-Scripts.sql" -Force
+ForEach-Object { Get-Content $_.FullName } |
+Set-Content -Path "$RepoRootPath/Install-All-Scripts.sql" -Force
 #append script to (re-)create SqlServerVersions Table (https://github.com/BrentOzarULTD/SQL-Server-First-Responder-Kit/issues/2429)
 if ( test-path "$SqlVersionsPath")
-	{ Add-Content -Path "$FilePath/Install-All-Scripts.sql" -Value (Get-Content -Path "$SqlVersionsPath")}
+	{ Add-Content -Path "$RepoRootPath/Install-All-Scripts.sql" -Value (Get-Content -Path "$SqlVersionsPath")}
 if ( test-path "$BlitzFirstPath")
-	{ Add-Content -Path "$FilePath/Install-All-Scripts.sql" -Value (Get-Content -Path "$BlitzFirstPath")}
+	{ Add-Content -Path "$RepoRootPath/Install-All-Scripts.sql" -Value (Get-Content -Path "$BlitzFirstPath")}