Update CI pipeline for pages

[ci deploy-pages]

.travis.yml

@@ -56,6 +56,9 @@ jobs:
         - mv docs/vectorbt/* docs
         - rmdir docs/vectorbt
         - mv docs/site/* .
+        - touch CNAME
+        - echo 'vectorbt.dev' > CNAME
+        - touch .nojekyll
       deploy:
         - provider: pages
           skip_cleanup: true

vectorbt/_settings.py

@@ -5,17 +5,51 @@
 
 `settings` config is also accessible via `vectorbt.settings`.
 
+Here are the main properties of the `settings` config:
+
+* It's a nested config, that is, a config that consists of multiple sub-configs.
+    one per sub-package (e.g., 'data'), module (e.g., 'array_wrapper'), or even class (e.g., 'configured').
+    Each sub-config may consist of other sub-configs.
+* It has frozen keys - you cannot add other sub-configs or remove the existing ones, but you can modify them.
+* Each sub-config can either inherit the properties of the parent one by using `dict` or overwrite them
+    by using its own `vectorbt.utils.config.Config`. The main reason for defining an own config is to allow
+    adding new keys (e.g., 'plotting.layout').
+
 For example, you can change default width and height of each plot:
+
 ```python-repl
 >>> import vectorbt as vbt
 
 >>> vbt.settings['plotting']['layout']['width'] = 800
 >>> vbt.settings['plotting']['layout']['height'] = 400
 ```
 
-Changes take effect immediately.
+The main sub-configs such as for plotting can be also accessed/modified using the dot notation:
+
+```
+>>> vbt.settings.plotting['layout']['width'] = 800
+```
+
+Some sub-configs allow the dot notation too but this depends whether they inherit the rules of the root config.
+
+```plaintext
+>>> vbt.settings.data - ok
+>>> vbt.settings.data.binance - ok
+>>> vbt.settings.data.binance.api_key - error
+>>> vbt.settings.data.binance['api_key'] - ok
+```
+
+Since this is only visible when looking at the source code, the advice is to always use the bracket notation.
 
 !!! note
+    Any change takes effect immediately. But whether its reflected immediately depends upon the place
+    that accesses the settings. For example, changing 'array_wrapper.freq` has an immediate effect because
+    the value is resolved every time `vectorbt.base.array_wrapper.ArrayWrapper.freq` is called.
+    On the other hand, changing 'portfolio.fillna_close' has only effect on `vectorbt.portfolio.base.Portfolio`
+    instances created in the future, not the existing ones, because the value is resolved upon the construction.
+    But mostly you can still force-update the default value by replacing the instance using
+    `vectorbt.portfolio.base.Portfolio.replace`.
+
     All places in vectorbt import `settings` from `vectorbt._settings.settings`, not from `vectorbt`.
     Overwriting `vectorbt.settings` only overwrites the reference created for the user.
     Consider updating the settings config instead of replacing it.

vectorbt/portfolio/base.py

@@ -308,6 +308,18 @@
 10
 ```
 
+## Defaults
+
+If you look at the arguments of each class method, you will notice that most of them default to None.
+None has a special meaning in vectorbt: it's a command to pull the default value from the global settings config
+- `vectorbt._settings.settings`. The branch for the `Portfolio` can be found under the key 'portfolio'.
+For example, the default size used in `Portfolio.from_signals` and `Portfolio.from_orders` is `np.inf`:
+
+```python-repl
+>>> vbt.settings.portfolio['size']
+inf
+```
+
 ## Grouping
 
 One of the key features of `Portfolio` is the ability to group columns. Groups can be specified by