Merge pull request #253 from SciML/pt_docs

add PT to docs

Author: ChrisRackauckas

docs/src/api/nonlinearsolve.md

@@ -7,6 +7,7 @@ These are the native solvers of NonlinearSolve.jl.
 ```@docs
 NewtonRaphson
 TrustRegion
+PseudoTransient
 ```
 
 ## Polyalgorithms

docs/src/solvers/NonlinearSystemSolvers.md

@@ -55,11 +55,14 @@ features, but have a bit of overhead on very small problems.
     improvements suggested in the [paper](https://arxiv.org/abs/1201.5885) "Improvements to
     the Levenberg-Marquardt algorithm for nonlinear least-squares minimization". Designed for
     large-scale and numerically-difficult nonlinear systems.
+  - `PseudoTransient()`: A pseudo-transient method which mixes the stability of Euler-type
+    stepping with the convergence speed of a Newton method. Good for highly unstable
+    systems.
   - `RobustMultiNewton()`: A polyalgorithm that mixes highly robust methods (line searches and
     trust regions) in order to be as robust as possible for difficult problems. If this method
     fails to converge, then one can be pretty certain that most (all?) other choices would
     likely fail.
-  - `FastShortcutNonlinearPolyalg`: The default method. A polyalgorithm that mixes fast methods
+  - `FastShortcutNonlinearPolyalg()`: The default method. A polyalgorithm that mixes fast methods
     with fallbacks to robust methods to allow for solving easy problems quickly without sacrificing
     robustnes on the hard problems.