copy subset of Sprig template functions

docs/sprig/url.md

@@ -0,0 +1,33 @@
+# URL Functions
+
+## urlParse
+Parses string for URL and produces dict with URL parts
+
+```
+urlParse "http://admin:secret@server.com:8080/api?list=false#anchor"
+```
+
+The above returns a dict, containing URL object:
+```yaml
+scheme:   'http'
+host:     'server.com:8080'
+path:     '/api'
+query:    'list=false'
+opaque:   nil
+fragment: 'anchor'
+userinfo: 'admin:secret'
+```
+
+For more info, check https://golang.org/pkg/net/url/#URL
+
+## urlJoin
+Joins map (produced by `urlParse`) to produce URL string
+
+```
+urlJoin (dict "fragment" "fragment" "host" "host:80" "path" "/path" "query" "query" "scheme" "http")
+```
+
+The above returns the following string:
+```
+proto://host:80/path?query#fragment
+```