Added XML decoder (#1044)

pkg/yqlib/doc/operators/load.md

@@ -0,0 +1,94 @@
+# Load
+
+The `load`/`strload` operator allows you to load in content from another file referenced in your yaml document.
+
+Note that you can use string operators like `+` and `sub` to modify the value in the yaml file to a path that exists in your system.
+
+Use `strload` to load text based content as a string block, and `load` to interpret the file as yaml.
+
+Lets say there is a file `../../examples/thing.yml`:
+
+```yaml
+a: apple is included
+b: cool
+```
+
+## Simple example
+Given a sample.yml file of:
+```yaml
+myFile: ../../examples/thing.yml
+```
+then
+```bash
+yq eval 'load(.myFile)' sample.yml
+```
+will output
+```yaml
+a: apple is included
+b: cool.
+```
+
+## Replace node with referenced file
+Note that you can modify the filename in the load operator if needed.
+
+Given a sample.yml file of:
+```yaml
+something:
+  file: thing.yml
+```
+then
+```bash
+yq eval '.something |= load("../../examples/" + .file)' sample.yml
+```
+will output
+```yaml
+something:
+  a: apple is included
+  b: cool.
+```
+
+## Replace _all_ nodes with referenced file
+Recursively match all the nodes (`..`) and then filter the ones that have a 'file' attribute. 
+
+Given a sample.yml file of:
+```yaml
+something:
+  file: thing.yml
+over:
+  here:
+    - file: thing.yml
+```
+then
+```bash
+yq eval '(.. | select(has("file"))) |= load("../../examples/" + .file)' sample.yml
+```
+will output
+```yaml
+something:
+  a: apple is included
+  b: cool.
+over:
+  here:
+    - a: apple is included
+      b: cool.
+```
+
+## Replace node with referenced file as string
+This will work for any text based file
+
+Given a sample.yml file of:
+```yaml
+something:
+  file: thing.yml
+```
+then
+```bash
+yq eval '.something |= strload("../../examples/" + .file)' sample.yml
+```
+will output
+```yaml
+something: |-
+  a: apple is included
+  b: cool.
+```
+