Added append equals, merge append. Fixed creating numeric arrays

pkg/yqlib/doc/Add.md

@@ -3,6 +3,31 @@ Add behaves differently according to the type of the LHS:
 - number scalars: arithmetic addition (soon)
 - string scalars: concatenate (soon)
 
+Use `+=` as append assign for things like increment. `.a += .x` is equivalent to running `.a |= . + .x`.
+
+## Concatenate and assign arrays
+Given a sample.yml file of:
+```yaml
+a:
+  val: thing
+  b:
+    - cat
+    - dog
+```
+then
+```bash
+yq eval '.a.b += ["cow"]' sample.yml
+```
+will output
+```yaml
+a:
+  val: thing
+  b:
+    - cat
+    - dog
+    - cow
+```
+
 ## Concatenate arrays
 Given a sample.yml file of:
 ```yaml

pkg/yqlib/doc/Assign.md

@@ -148,7 +148,7 @@ Given a sample.yml file of:
 ```
 then
 ```bash
-yq eval '.a.b[0] |= "bogs"' sample.yml
+yq eval '.a.b.[0] |= "bogs"' sample.yml
 ```
 will output
 ```yaml

pkg/yqlib/doc/Multiply.md

@@ -2,6 +2,8 @@ Like the multiple operator in `jq`, depending on the operands, this multiply ope
 
 Upcoming versions of `yq` will add support for other types of multiplication (numbers, strings).
 
+To concatenate when merging objects, use the `*+` form (see examples below). This will recursively merge objects, appending arrays when it encounters them.
+
 Note that when merging objects, this operator returns the merged object (not the parent). This will be clearer in the examples below.
 
 ## Merging files
@@ -66,9 +68,9 @@ b:
 Given a sample.yml file of:
 ```yaml
 a: {things: great}
-	b:
-	  also: "me"
-	
+b:
+  also: "me"
+
 ```
 then
 ```bash
@@ -76,6 +78,9 @@ yq eval '. * {"a":.b}' sample.yml
 ```
 will output
 ```yaml
+a: {things: great, also: "me"}
+b:
+  also: "me"
 ```
 
 ## Merge arrays

pkg/yqlib/doc/Traverse.md

@@ -138,7 +138,7 @@ Given a sample.yml file of:
 ```
 then
 ```bash
-yq eval '[0]' sample.yml
+yq eval '.[0]' sample.yml
 ```
 will output
 ```yaml
@@ -152,7 +152,7 @@ Given a sample.yml file of:
 ```
 then
 ```bash
-yq eval '[2]' sample.yml
+yq eval '.[2]' sample.yml
 ```
 will output
 ```yaml
@@ -166,7 +166,7 @@ a: b
 ```
 then
 ```bash
-yq eval '[0]' sample.yml
+yq eval '.[0]' sample.yml
 ```
 will output
 ```yaml

pkg/yqlib/doc/headers/Add.md

@@ -2,3 +2,5 @@ Add behaves differently according to the type of the LHS:
 - arrays: concatenate
 - number scalars: arithmetic addition (soon)
 - string scalars: concatenate (soon)
+
+Use `+=` as append assign for things like increment. `.a += .x` is equivalent to running `.a |= . + .x`.

pkg/yqlib/doc/headers/Multiply.md

@@ -2,6 +2,8 @@ Like the multiple operator in `jq`, depending on the operands, this multiply ope
 
 Upcoming versions of `yq` will add support for other types of multiplication (numbers, strings).
 
+To concatenate when merging objects, use the `*+` form (see examples below). This will recursively merge objects, appending arrays when it encounters them.
+
 Note that when merging objects, this operator returns the merged object (not the parent). This will be clearer in the examples below.
 
 ## Merging files