Update .gitignore

- Ignore `build` from docker compose.
- Remove redundant lines.

Author: martincostello

.gitignore

@@ -17,6 +17,7 @@
 mono_crash.*
 
 # Build results
+[Bb]uild/
 [Dd]ebug/
 [Dd]ebugPublic/
 [Rr]elease/
@@ -243,14 +244,6 @@ ClientBin/
 *.publishsettings
 orleans.codegen.cs
 
-# Including strong name files can present a security risk
-# (https://github.com/github/gitignore/pull/2483#issue-259490424)
-#*.snk
-
-# Since there are multiple workflows, uncomment next line to ignore bower_components
-# (https://github.com/github/gitignore/pull/1529#issuecomment-104372622)
-#bower_components/
-
 # RIA/Silverlight projects
 Generated_Code/